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ОглавлениеA less definite relationship between the sponges and polyzoa of the Malabar Zone and those of countries to the east of India is suggested by the following facts:—
(1) The occurrence of the genus Corvospongilla in Burma; (2) the occurrence of the subgenus Stratospongilla in Sumatra, China, and the Philippines; (3) the occurrence of a race of Lophopodella carteri in Japan; (4) the occurrence of a species allied to Plumatella tanganyikæ in the Philippines.
It will be noted that in each of these instances the relationship extends to Africa as well as to the Eastern countries, and is more marked in the former direction. The species of Stratospongilla, moreover, that occurs in Sumatra (S. sumatrensis) also occurs in Africa, while those that have been found in China and the Philippines are aberrant forms.
At first sight it might appear that these extra-Indian relationships might be explained by supposing that gemmules and statoblasts were brought to the Malabar Coast from Africa by the aërial currents of the monsoon or by marine currents and carried from India eastwards by the same agency, this agency being insufficient to transport them to the interior and the eastern parts of the Peninsula. The work of La Touche[E] on wind-borne foraminifera in Rajputana is very suggestive in this direction; but that the peculiar sponge and polyzoon fauna of Malabar is due to the agency either of wind or of marine currents may be denied with confidence, for it is a striking fact that most of the characteristic genera and subgenera of the Zone have resting reproductive bodies that are either fixed to solid objects or else are devoid of special apparatus to render them light. The former is the case as regards all species of Corvospongilla and all Indian and most other species of Stratospongilla, the gemmules of which not only are unusually heavy but also adhere firmly; while the statoblasts of Fredericella have no trace of the air-cells that render the free statoblasts of all other genera of phylactolæmatous polyzoa peculiarly light and therefore peculiarly liable to be transported by wind.
A true geographical or geological explanation must therefore be sought for the relationship between the sponges and polyzoa of Malabar, of Africa, and of the Eastern countries—a relationship that is well known to exist as regards other groups of animals. No more satisfactory explanation has as yet been put forward than that of a former land connection between Africa and the Malaysia through Malabar at a period (probably late Cretaceous) when the Western Ghats were much higher than they now are[F].
There is little to be said as regards the distribution of the sponges, hydroids, and polyzoa of fresh water in other parts of India. It may be noted, however, that the species known from the Punjab are all widely distributed Palæarctic forms, and that the genus Stolella is apparently confined to the Indo-Gangetic Plain. Two species of sponge are peculiar to Lower Burma, one of them (Corvospongilla burmanica) representing the geographical alliance already discussed as regards the Malabar Zone, the other (Tubella vesparioides) closely related to a Malaysian species (T. vesparium from Borneo) and perhaps representing the northern limit of the Malaysian element well known in the fauna of Lower Burma. Of the sponges and polyzoa of Ceylon we know as yet too little to make it profitable to discuss their affinities. All that have as yet been discovered occur also in Peninsular India; nor do they afford any evidence of a connection with the Malabar Zone.
The question of the geographical range of the sponges, hydroids, and polyzoa of brackish water may be considered briefly, for it is of importance in considering that of those which are confined to fresh water. Some of these species from brackish water (e. g., Membranipora lacroixii) are identical with others (e. g., Victorella bengalensis and Bowerbankia caudata subsp. bengalensis) closely related to European forms. Others again (e. g., Loxosomatoides colonialis and Sagartia schilleriana) are known as yet from the Ganges delta only. In our ignorance of the Indian representatives of the groups to which they belong, it is impossible to assert that their distribution is actually so restricted as it seems.
Some Special Localities.
In order to avoid constant repetition as regards the conditions that prevail at the places most frequently mentioned in this volume, a few details as regards them may be conveniently stated here.
Lower Bengal.
Calcutta is situated on the River Hughli at a point about 90 miles from the open sea. The water of the river is practically fresh, but is strongly affected by the tides; it is always turbid and of a brownish colour. The river, however, is not a good collecting ground for sponges, cœlenterates, and polyzoa, and none of the species described in this volume have been obtained from it. It is in the Calcutta "tanks" that most of my investigations have been made. These tanks are ponds, mostly of artificial origin, very numerous, of varying size but never very large or deep. Most of them contain few solid objects to which sedentary organisms can fix themselves, and such ponds are of course poor in sponges and polyzoa. Others, however, support a prolific growth of weeds such as Pistia stratiotes, Lemna, and Limnanthemum, and a few have brickwork or artificial stonework at their sides. In those parts of the town that approach the Salt Lakes (large lagoons and swamps of brackish water connected with the sea by the Mutlah River) the water of the ponds is slightly brackish and permits few plants except algæ to flourish. Few of the bigger tanks ever dry up. The best of the tanks from the sponge-collector's point of view, so far as I have been able to discover, is the one in the compound of the Indian Museum. It enjoys all the advantages of light and shade, solid supports, prolific aquatic vegetation, considerable depth, and the vicinity of human dwellings that seem to be favourable to the growth of sponges, no less than nine species of which, representing three genera and two subgenera, grow abundantly in it. Hydra also flourishes in this pond, but for some reasons there are few polyzoa. The phylactolæmatous species of the latter group, however, are extraordinarily abundant in one of the tanks in the Zoological Gardens at Alipore. In this tank, which unlike the Museum tank is directly connected with the river, no less than six species and varieties of the genus Plumatella have been found growing together on sticks, floating seeds, and water-plants. Except Hislopia, which is common on Vallisneria in one tank on the Maidan (opposite the Bengal Club), the ctenostomes of stagnant water are only found in the tanks near the Salt Lakes.
Port Canning is situated on the Mutlah River about 30 miles from Calcutta and about 60 from the open sea. The Mutlah is really a tidal creek rather than a river, in spite of the fact that it runs for a considerable number of miles, and its waters are distinctly brackish. Water taken from the edge at Port Canning in March was found to contain 25.46 per thousand of saline residue. The interesting feature of Port Canning, however, is from a zoological point of view not the Mutlah but certain ponds of brackish water now completely separated from it, except occasionally when the river is in flood, but communicating regularly with it in the memory of living persons. These ponds, which were apparently not in existence in 1855, have on an average an area of about half an acre each, and were evidently formed by the excavation of earth for the construction of an embankment along the Mutlah. They are very shallow and lie exposed to the sun. The salinity differs considerably in different ponds, although the fauna seems to be identical; the water of one pond was found to contain 22.88 per thousand of saline residue in May, 20.22 per thousand in March, and 12.13 in December. A second pond in the neighbourhood of the first and apparently similar to it in every way contained only 9.82 per thousand in July, after the rains had broken. The fauna of these ponds includes not only a freshwater sponge (Spongilla alba var. bengalensis) but also many aquatic insects (e. g., larvæ of mosquitos and of Chironomus and several species of beetles and Rhynchota); while on the other hand essentially marine cœlenterates (Irene ceylonensis, etc.) and worms (e. g., the gephyrean Physcosoma lurco[G]) form a part of it, together with forms of intermediate habitat such as Bowerbankia caudata subsp. bengalensis, Victorella bengalensis, and several fish and crustacea common in brackish water.
Orissa.
Orissa may be described in general terms as consisting of the coastal area of Bengal south of the Gangetic delta. It extends in inland, however, for a considerable distance and includes hilly tracts. There is no geographical boundary between it and the north-eastern part of the Madras Presidency or the eastern part of the Central Provinces.
Chilka Lake.—This marine lake is a shallow lagoon measuring about 40 miles in length and 10 miles in breadth, and formed in geologically recent times by the growth of a narrow sand-bank across the mouth of a wide bay. At its northern end it communicates with the sea by a narrow channel, and throughout its length it is strongly affected by the tides. At its south end, which is actually situated in the Ganjam district of Madras, the water is distinctly brackish and is said to be nearly fresh at certain times of year. At this end there are numerous small artificial pools of brackish water somewhat resembling those of Port Canning as regards their fauna.
Sur (or Sar) Lake.—A shallow, freshwater lake of very variable size situated a few miles north of Puri on the Orissa coast. In origin it probably resembled the Chilka Lake, but it is now separated from the sea by about 3 miles of barren sand dunes, among which numerous little pools of rain-water are formed during the rains. These dry up completely in winter, and even the lake itself is said sometimes almost to disappear, although when it is full it is several miles in length. The fauna is essentially a freshwater one, but includes certain Mysidæ and other crustacea usually found in brackish water.
Bombay Presidency.
Bombay.—The town of Bombay, built on an island near the mainland, is situated close to swamps and creeks of brackish water not unlike those that surround Calcutta. Its "tanks," however, differ from those of Calcutta in having rocky bottoms and, in many cases, in drying up completely in the hot weather. Of the fauna of the swamps extremely little is known, but so far as the sponges and polyzoa of the tanks are concerned the work undertaken by Carter was probably exhaustive.
Igatpuri.—Igatpuri is situated at an altitude of about 2000 feet, 60 miles north-east of Bombay. Above the town there is a lake of several square miles in area whence the water-supply of several stations in the neighbourhood is obtained. The water is therefore kept free from contamination. The bottom is composed of small stones and slopes gradually up at the edges. During the dry weather its level sinks considerably. Several interesting sponges and polyzoa have been found in this lake, most of them also occurring in a small pond in the neighbourhood in which clothes are washed and the water is often full of soap-suds.
Southern India.
Madras.—The city of Madras is built by the sea, straggling over a large area of the sandy soil characteristic of the greater part of the east coast of India. In wet weather this soil retains many temporary pools of rain-water, and there are numerous permanent tanks of no great size in the neighbourhood of the town. The so-called Cooum River, which flows through the town, is little more than a tidal creek, resembling the Mutlah River of Lower Bengal on a much smaller scale. The sponges and polyzoa as yet found in the environs of Madras are identical with those found in the environs of Calcutta.
Bangalore.—Bangalore (Mysore State) is situated near the centre of the Madras Presidency on a plateau about 3000 feet above sea-level. The surrounding country is formed of laterite rock which decomposes readily and forms a fine reddish silt in the tanks. These tanks are numerous, often of large size, and as a rule at least partly of artificial origin. Their water supports few phanerogamic plants and is, as my friend Dr. Morris Travers informs me, remarkably free from salts in solution. The sponge fauna of the neighbourhood of Bangalore appears to be intermediate between that of Madras and that of Travancore.
The Backwaters of Cochin and Travancore.—The "backwaters" of Cochin and Travancore were originally a series of shallow lagoons stretching along the coast of the southern part of the west coast of India for a distance of considerably over a hundred miles. They have now been joined together by means of canals and tunnels to form a tidal waterway, which communicates at many points directly with the sea. The salinity of the water differs greatly at different places and in different seasons, and at some places there is an arrangement to keep out sea-water while the rice-fields are being irrigated. The fauna is mainly marine, but in the less saline parts of the canals and lakes many freshwater species are found.
Shasthancottah.—There are two villages of this name, one situated on the backwater near Quilon (coast of Travancore), the other about three miles inland on a large freshwater lake. This lake, which does not communicate with the backwater, occupies a narrow winding rift several miles in length at a considerable depth below the surrounding country. Its bottom is muddy and it contains few water-plants, although in some places the water-plants that do exist are matted together to form floating islands on which trees and bushes grow. The fauna, at any rate as regards mollusca and microscopic organisms, is remarkably poor, but two species of polyzoa (Fredericella indica and Plumatella fruticosa) and one of sponge (Trochospongilla pennsylvanica) grow in considerable abundance although not in great luxuriance.
The Himalayas.
Bhim Tal[H] is a lake situated at an altitude of 4500 feet in that part of the Western Himalayas known as Kumaon, near the plains. It has a superficial area of several square miles, and is deep in the middle. Its bottom and banks are for the most part muddy. Little is known of its fauna, but two polyzoa (Plumatella allmani and Lophopodella carteri) and the gemmules of two sponges (Spongilla carteri and Ephydatia meyeni) have been found in it.
* * * * *
Nomenclature and Terminology.
The subject of nomenclature may be considered under four heads:—(I.) the general terminology of the various kinds of groups of individuals into which organisms must be divided; (II.) the general nomenclature of specimens belonging to particular categories, such as types, co-types, etc.; (III.) the nomenclature that depends on such questions as that of "priority"; and (IV.) the special terminology peculiar to the different groups. The special terminology peculiar to the different groups is dealt with in the separate introductions to each of the three parts of this volume.
(I.)
No group of animals offers greater difficulty than the sponges, hydroids, and polyzoa (and especially the freshwater representatives of these three groups) as regards the question "What is a species?" and the kindred questions, "What is a subspecies?" "What is a variety?" and "What is a phase?" Genera can often be left to look after themselves, but the specific and kindred questions are answered in so many different ways, if they are even considered, by different systematists, especially as regards the groups described in this volume, that I feel it necessary to state concisely my own answers to these questions, not for the guidance of other zoologists but merely to render intelligible the system of classification here adopted. The following definitions should therefore be considered in estimating the value of "species," etc., referred to in the following pages.
Species.—A group of individuals differing in constant characters of a definite nature and of systematic[I] importance from all others in the same genus.
Subspecies.—An isolated or local race, the individuals of which differ from others included in the same species in characters that are constant but either somewhat indefinite or else of little systematic importance.
Variety.—A group of individuals not isolated geographically from others of the same species but nevertheless exhibiting slight, not altogether constant, or indefinite differences from the typical form of the species (i. e., the form first described).
Phase.—A peculiar form assumed by the individuals of a species which are exposed to peculiarities in environment and differ from normal individuals as a direct result.
There are cases in which imperfection of information renders it difficult or impossible to distinguish between a variety and a subspecies. In such cases it is best to call the form a variety, for this term does not imply any special knowledge as regards its distribution or the conditions in which it is found.
I use the term "form" in a general sense of which the meaning or meanings are clear without explanation.
(II.)
The question of type specimens must be considered briefly. There are two schools of systematists, those who assert that one specimen and one only must be the type of a species, and those who are willing to accept several specimens as types. From the theoretical point of view it seems impossible to set up any one individual as the ideal type of a species, but those who possess collections or are in charge of museums prefer, with the natural instinct of the collector, to have a definite single type (of which no one else can possibly possess a duplicate) in their possession or care, and there is always the difficulty that a zoologist in describing a species, if he recognizes more than one type, may include as types specimens that really belong to more than one species. These difficulties are met by some zoologists by the recognition of several specimens as paratypes, all of equal value; but this, after all, is merely a terminological means of escaping from the difficulty, calculated to salve the conscience of a collector who feels unwilling to give up the unique type of a species represented by other specimens in his collection. The difficulty as regards the confounding of specimens of two or more species as the types of one can always be adjusted if the author who discovers the mistake redescribes one of the species under the original name and regards the specimen that agrees with his description as the type, at the same time describing a new species with another of the specimens as its type. Personally I always desire to regard the whole material that forms the basis of an original description of a species as the type, but museum rules often render this impossible, and the best that can be done is to pick out one specimen that seems particularly characteristic and to call it the type, the rest of the material being termed co-types. A peculiar difficulty arises, however, as regards many of the sponges, cœlenterates, and polyzoa, owing to the fact that they are often either compound animals, each specimen consisting of more than one individual, or are easily divisible into equivalent fragments. If the single type theory were driven to its logical conclusion, it would be necessary to select one particular polyp in a hydroid colony, or even the part of a sponge that surrounded a particular osculum as the type of the species to which the hydroid or the sponge belonged. Either by accident or by design specimens of Spongillidæ, especially if kept dry, are usually broken into several pieces. There is, as a matter of fact, no reason to attribute the peculiarly sacrosanct nature of a type to one piece more than another. In such cases the biggest piece may be called the type, while the smaller pieces may be designated by the term "schizotype."
The more precise definition of such terms as topotype, genotype, et hujus generis omnis is nowadays a science (or at any rate a form of technical industry) by itself and need not be discussed here.
(III.)
In 1908 an influential committee of British zoologists drew up a strenuous protest against the unearthing of obsolete zoological names (see 'Nature,' Aug. 1908, p. 395). To no group does this protest apply with greater force than to the three discussed in this volume. It is difficult, however, to adopt any one work as a standard of nomenclature for the whole of any one of them. As regards the Spongillidæ it is impossible to accept any monograph earlier than Potts's "Fresh-Water Sponges" (P. Ac. Philad., 1887), for Bowerbank's and Carter's earlier monographs contained descriptions of comparatively few species. Even Potts's monograph I have been unable to follow without divergence, for it seems to me necessary to recognize several genera and subgenera that he ignored. The freshwater polyzoa, however, were dealt with in so comprehensive a manner by Allman in his "Fresh-Water Polyzoa" (London, 1856) that no difficulty is experienced in ignoring, so far as nomenclature is concerned, any earlier work on the group; while as regards other divisions of the polyzoa I have followed Hincks's "British Marine Polyzoa" (1880), so far as recent researches permit. In most cases I have not attempted to work out an elaborate synonymy of species described earlier than the publication of the works just cited, for to do so is a mere waste of time in the case of animals that call for a most precise definition of species and genera and yet were often described, so far as they were known earlier than the dates in question, in quite general terms. I have been confirmed in adopting this course by the fact that few of the types of the earlier species are now in existence, and that a large proportion of the Indian forms have only been described within the last few years.
Material.
The descriptions in this volume are based on specimens in the collection of the Indian Museum, the Trustees of which, by the liberal manner in which they have permitted me to travel in India and Burma on behalf of the Museum, have made it possible not only to obtain material for study and exchange but also to observe the different species in their natural environment. This does not mean to say that specimens from other collections have been ignored, for many institutions and individuals have met us generously in the matter of gifts and exchanges, and our collection now includes specimens of all the Indian forms, named in nearly all cases by the author of the species, except in those of species described long ago of which no authentic original specimens can now be traced. Pieces of the types of all of the Indian Spongillidæ described by Carter have been obtained from the British Museum through the kind offices of Mr. R. Kirkpatrick. The Smithsonian Institution has sent us from the collection of the United States National Museum specimens named by Potts, and the Berlin Museum specimens named by Weltner, while to the Imperial Academy of Sciences of St. Petersburg we owe many unnamed but interesting sponges. Dr. K. Kraepelin and Dr. W. Michaelsen have presented us with specimens of most of the species and varieties of freshwater polyzoa described by the former in his great monograph and elsewhere. We owe to Dr. S. F. Harmer, formerly of the Cambridge University Museum and now Keeper in Zoology at the British Museum, to Professor Max Weber of Amsterdam, Professor Oka of Tokyo, and several other zoologists much valuable material. I would specially mention the exquisite preparations presented by Mr. C. Rousselet. Several naturalists in India have also done good service to the Museum by presenting specimens of the three groups described in this volume, especially Major H. J. Walton, I.M.S., Major J. Stephenson, I.M.S., Dr. J. R. Henderson and Mr. G. Matthai of Madras, and Mr. R. Shunkara Narayana Pillay of Trivandrum.
The following list shows where the types of the various species, subspecies, and varieties are preserved, so far as it has been possible to trace them. I have included in this list the names of all species that have been found in stagnant water, whether fresh or brackish, but those of species not yet found in fresh water are enclosed in square brackets.
Indian Spongillidæ. | ||
---|---|---|
Name. | Type in Coll. | Material Examined. |
Spongilla lacustris subsp. reticulata | Ind. Mus. | Type. |
Spongilla proliferens | Ind. Mus. | Type. |
Spongilla alba | Brit. and Ind. Mus. | Schizotype. |
[Spongilla alba var. bengalensis] | Ind. Mus. | Type. |
Spongilla alba var. cerebellata | Brit. Mus. | Specimens compared with type. |
Spongilla cinerea | Brit. and Ind. Mus. | Schizotype. |
[Spongilla travancorica] | Ind. Mus. | Type. |
Spongilla hemephydatia | Ind. Mus. | Type. |
Spongilla crateriformis | U.S. Nat. Mus. | Co-type. |
Spongilla carteri | Brit. and Ind. Mus. | Schizotype. |
Spongilla carteri var. mollis | Ind. Mus. | Type. |
Spongilla carteri var. cava | Ind. Mus. | Type. |
Spongilla carteri var. lobosa | Ind. Mus. | Type. |
Spongilla fragilis subsp. calcuttana | Ind. Mus. | Type. |
Spongilla fragilis subsp. decipiens | Amsterdam Mus. | Co-type. |
Spongilla gemina | Ind. Mus. | Type. |
Spongilla crassissima | Ind. Mus. | Type. |
Spongilla crassissima var. crassior | Ind. Mus. | Type. |
Spongilla bombayensis | Brit. and Ind. Mus. | Schizotype. |
Spongilla indica | Ind. Mus. | Type. |
Spongilla ultima | Ind. Mus. | Type. |
Pectispongilla aurea | Ind. Mus. | Type. |
Ephydatia meyeni | Brit. and Ind. Mus. | Schizotype. |
Dosilia plumosa | Brit. and Ind. Mus. | Schizotype. |
Trochospongilla latouchiana | Ind. Mus. | Type. |
Trochospongilla phillottiana | Ind. Mus. | Type. |
Trochospongilla pennsylvanica | U.S. Nat. Mus. | Co-type. |
Tubella vesparioides | Ind. Mus. | Type. |
Corvospongilla burmanica | Brit. and Ind. Mus. | Schizotype. |
Corvospongilla lapidosa | Ind. Mus. | Type. |
Indian Cœlenterates of Stagnant Water. | ||
Hydrozoa. | ||
Hydra oligactis | Not in existence. | |
Hydra vulgaris | Not in existence. | |
[Syncoryne filamentata] | Ind. Mus. | Type. |
[Bimeria vestita] | ? Not in existence. | |
[Irene ceylonensis] | Hydroid in Ind. Mus., Medusa in Brit. Mus. | Hydroid type. |
Actiniaria. | ||
[Sagartia schilleriana] | Ind. Mus. | Types. |
[Sagartia schilleriana subsp. exul] | Ind. Mus. | Type. |
Indian Polyzoa of Stagnant Water. | ||
Entoprocta. | ||
[Loxosomatoides colonialis] | Ind. Mus. | Types. |
Ectoprocta Cheilostomata. | ||
[Membranipora lacroixii] | ? Paris Mus. | |
[Membranipora bengalensis] | Ind. Mus. | Types. |
Ectoprocta Stenostomata. | ||
[Bowerbankia caudata subsp. bengalensis] | Ind. Mus. | Types. |
Victorella bengalensis | Ind. Mus. | Types. |
Hislopia lacustris | ? Not in existence. | |
Hislopia lacustris subsp. moniliformis | Ind. Mus. | Types. |
Ectoprocta Phylactolæmata. | ||
Fredericella indica | Ind. Mus. | Type. |
Plumatella fruticosa | Not in existence. | |
Plumatella diffusa | ? Philadelphia Acad.[J] | |
Plumatella allmani | Not in existence. | |
Plumatella emarginata | Not in existence. | |
Plumatella javanica | Hamburg and Ind. Mus. | One of the types. |
Plumatella tanganyikæ | Brit. and Ind. Mus. | One of the types. |
Stolella indica | Ind. Mus. | Type. |
Lophopodella carteri | Brit. Mus. | Type. |
Lophopodella carteri var. himalayana | Ind. Mus. | Type. |
Pectinatella burmanica | Ind. Mus. | Type. |
The literature dealing with the various groups described in the volume is discussed in the introductions to the three parts. Throughout the volume I have, so far as possible, referred to works that can be consulted in Calcutta in the libraries of the Indian Museum, the Geological Survey of India, or the Asiatic Society of Bengal. The names of works that are not to be found in India are marked with a *. The rarity with which this mark occurs says much for the fortunate position in which zoologists stationed in Calcutta find themselves as regards zoological literature, for I do not think that anything essential has been omitted.
It remains for me to express my gratitude to those who have assisted me in the preparation of this volume. The names of those who have contributed specimens for examination have already been mentioned. I have to thank the Trustees of the Indian Museum not only for their liberal interpretation of my duties as an officer of the Museum but also for the use of all the drawings and photographs and some of the blocks from which this volume is illustrated. Several of the latter have already been used in the "Records of the Indian Museum." From the Editor of the "Fauna" I have received valuable suggestions, and I am indebted to Dr. Weltner of the Berlin Museum for no less valuable references to literature. Mr. F. H. Gravely, Assistant Superintendent in the Indian Museum, has saved me from several errors by his criticism.
The majority of the figures have been drawn by the draftsmen of the Indian Museum, Babu Abhoya Charan Chowdhary, and of the Marine Survey of India, Babu Shib Chandra Mondul, to both of whom I am much indebted for their accuracy of delineation.
No work dealing with the sponges of India would be complete without a tribute to the memory of H. J. Carter, pioneer in the East of the study of lower invertebrates, whose work persists as a guide and an encouragement to all of us who are of the opinion that biological research on Indian animals can only be undertaken in India, and that even systematic zoological work can be carried out in that country with success. I can only hope that this, the first volume in the official Fauna of the Indian Empire to be written entirely in India, may prove not unworthy of his example.
Indian Museum, Calcutta Oct. 23rd, 1910.
[A] "L'origine des animaux d'eau douce," Bull. de l'Acad. roy. de Belgique (Classe des Sciences), No. 12, 1905, p. 724.
[B] Cat. Ind. Dec. Crust. Coll. Ind. Mus., part i, fasc. ii (Potamonidæ), 1910.
[C] I include Baluchistan in this territory largely for climatic reasons.
[D] Mr. S. W. Kemp recently obtained at Mangaldai, near the Bhutan frontier of Assam, a single specimen of what may be a species of Fredericella.
[E] See Mem. Geol. Surv. Ind. xxxv (1), p. 39 (1902).
[F] See Ortmann, "The Geographical Distribution of Freshwater Decapods and its bearing upon Ancient Geography," Proc. Amer. Phil. Soc. xli, p. 380, fig. 6 (1902); also Suess, "The Face of the Earth" (English ed.) i, p. 416 (1904).
[G] I am indebted to Mr. W. F. Lanchester for the identification of this species.
[H] The fauna of this lake and of others in the neighbourhood has recently been investigated by Mr. S. W. Kemp. See the addenda at the end of this volume.—June 1911.
[I] "What characters are of systematic importance?" is a question to which different answers must be given in the case of different groups.
[J] I have failed to obtain from the Philadelphia Academy of Science a statement that the type of this species is still in existence.