184 



AEACHNIDA. 



CHAPTER XII. 



Aeachnida.* 



The Arachnidans, long confounded with the Insects, 

 and still commonly described as such, are distin- 

 guished from the true members of the insect world 

 by characters so conspicuous, that the necessity for 

 considering them as a distinct class must be obvious 

 to anv one. 



Fig. 144.— irrDEr.s. 



In Insects, as we have seen above, the body pre- 

 sents three principal divisions, the head, the thorax, 

 and the abdomeyi ; but in the spider tribes, the blood- 



* apax'vi], aractme, a spider. 



