METAZOA ARACHNOZOA. 371 



runs down the radial non-adhesive threads to get it, or 

 when alarmed it hurries down a special thread, made for 

 the purpose, to its nest (in the upper right hand corner of 

 PI. 918.) 



The characters of this genus are typical. As in most 

 spiders, the small, flattened cephalothorax is connected 

 with the large, plump abdomen by an extremely narrow 

 waist (PI. 917, fig. i ; fig. 2, a}. The eyes in all Arach- 

 nida are single, and in this species there are eight (fig. i) 

 of which six are figured near the front edge of the cepha- 

 lothorax. The Peckhams 1 have shown that different 

 species of spiders can see from one or two inches to 

 twelve inches, and in the opinion of these investigators 

 they have the power of distinguishing colors. 



Epeira, like all spiders,, has no antennae, but according 

 to Emerton, both the palpi and first pair of legs at times 

 perform the function of these organs. The mandibles 

 are strong, black organs (fig. 2, d) which move laterally 

 and are provided with sharp fangs through which the 

 poison flows. The only other mouth parts are the two 

 maxillae (fig. 2.e) which bear the palpi that are enlarged 

 in the male (No. 916, specimen on the right) and used 

 as organs of copulation. 



The long seven-jointed legs (PI. 917, fig. 2, b) are pro- 

 vided with claws that are admirably adapted for walking 

 on a web. 



The abdomen bears three pairs of spinnerets (fig. 

 2, j) which represent as many pairs of legs. The third 

 pair are short and not distinctly seen until the other two 

 pairs are separated. Each of these spinnerets bears 

 many minute horny tubes from which the jets of liquid 

 matter issue, almost immediately solidifying, while the 

 feet of the spider unite the strands into a cord of cob- 

 web. The anus (fig. 2, n) is situated a little behind the 



1 The Sense of Sight in Spiders, Trans. Wisconsin Acad. Sci. 

 Arts and Letters, X, 1894, p. 249. 



