BRANCH ARTHROPODS , CLASS ARACHNID A : SPIDERS 231 



known in southern North America. Their sting though 

 painful is not dangerous to man. The young are born 

 alive and are carried about by the mother for some time 

 after birth. 



The mites (figs. 90 and 91) and ticks (fig. 92) are 

 mostly small obscure animals, which live more or less 

 parasitically. The common red spider of house-plants 

 as well as the sugar- and cheese-mites, the dreaded 



FIG. 91. Bird mite, species undetermined, from the gnome-owl, Glauci- 

 dium gnomus. (Photo-micrograph by Geo. O. Mitchell.) 



itch-mite and the chigger are familiar examples of these 

 degraded arachnids, and the wood-ticks, dog- and 

 chicken-ticks are common examples of the larger blood- 

 sucking forms. The body in both mites and ticks is very 

 compact, the two body-regions, cephalothorax and ab- 

 domen, being closely fused. 



The spiders have the abdomen distinctly set off from the 

 cephalothorax. The eyes (fig. 93) vary in number and 

 arrangement, the mandibles are large, each being com- 

 posed of two parts, a basal hair-covered part, the falx, and 

 a terminal smooth, shining, slender, sharp-pointed part, 



