456 



ZOOLOGY. 



general less solid than that of insects, and their body is com- 

 posed of two principal parts, almost always distinct ; the one 

 called cephalothorax, because it is formed by the head and 

 thorax confounded into a single segment ; the other named 

 abdomen, and composed sometimes of a series of distinct 



Fig. 495. Mygale, Cuv. Aranea avicularia, Lin. ; Crab Spider. 



rings, as may be seen in scorpions (Fig. 499) ; sometimes of a 

 soft mass, globular, and without divisions, as, for example, in 

 spiders (Fig. 495).* 



* The arachnides are divided into two orders, the pulmonaria and the 

 trachearia. The first includes such genera as the aranea, the tarantula, 

 scorpio, &c. The second order includes the phalangida, with its various 

 orders of siro, trogulus, &c., and the acarus, of which there are many sub- 

 genera and species. B. K. 



