Читать книгу The Common Spiders of the United States - J. H. Emerton - Страница 5

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The Drassidæ, like the Lycosidæ (p. 67), are ground spiders, though some genera, like Anyphæna (p. 12) and Clubiona (p. 15), are equally common in summer on bushes. They make nests in the form of a bag or flattened tube, but no cobwebs for catching insects, and are commonly found running about among dead leaves and short grass and sometimes even on bare ground and sand. In form they are usually two or three times as long as they are wide, like the Lycosidæ (p. 67), but more often flattened on the back. The legs differ but little in length, and the first and second pairs are directed forward, the third and fourth backward. Their hairs and spines are short, giving them a smooth, velvet-like appearance. The feet have two claws, with a brush of flattened hairs under them, like the Thomisidæ and Attidæ (p. 41), but unlike the Lycosidæ (p. 67), which have three claws. The mandibles are large and strong and are together as wide as the head. The eyes are all about the same size and arranged in two rows of about the same length and not far apart, but between different species there are slight differences in their arrangement. The colors are usually dull gray, brown, and black, with few markings or none. A few species are very brightly marked, as in Micaria (p. 9) and Pœilochroa (p. 4).

There are three groups among the Drassidæ:

1. Prosthesima, Gnaphosa, Pœcilochroa, Pythonissa, and Drassus, which are generally dark in color and flattened above, with the cephalothorax narrow in front and the eyes covering about half the width of the head and differing in their relative positions among the different genera. The labium is long and the maxillæ slightly widened at the end, or with the outer corners rounded off and sometimes a crease or depression in the middle. The joints of the first legs are sometimes thickened in the middle. The lower spinnerets are longer than the others and flat on the end.

2. Micaria, Geotrecha, Phrurolithus, Agrœca, and Anyphæna, in which the body is less flattened, the legs longer, and the movements quicker. The colors are lighter and more varied. The labium is short and the maxillæ with straight sides.

3. Clubiona, Chiracanthium, and Trachelas, in which the colors are plain and light, the eyes spread over more than half the front of the head and close to its front edge. The labium is as long as it is in Drassus, but contracted at the base. The maxillæ are narrow in the middle and flat and wide at the ends.