ARACHNIDA. 283 



the abdomen. In the spider (Fig. 136, where 



c is the cephalo-thorax, 

 and A the abdomen) these 

 two portions of the body 

 are separated by a deep 

 groove, which leaves only 

 a slender pedicle, or tube 

 of communication be- 

 tween them. There are usually in the male 

 four pair of legs, constantly articulated with the 

 cephalo-thorax ; but the female is furnished with 

 an additional pair, to enable her to carry her 

 eggs. For the purpose of obtaining an extensive 

 base of support, the feet of the spider are spread 

 out in diverging rays, so as to include a very 

 wide circle. They are divided into several joints, 

 those next to the body being termed the haunches, 

 and the succeeding ones the leg, and the tarsus, 

 and each foot is terminated by two, or sometimes 

 three hooks. Besides these, there are other 

 members, resembling feet, which are placed in 

 front of the head, and have affixed to them either 

 a moveable hook, or pincers, which are employed 

 as organs of prehension, and of offence. Through 

 the larger branches of these a canal passes, 

 which opens near the point, and conducts a 

 poisonous fluid into the wounds inflicted by this 

 formidable weapon. 



In common with all articulated animals, 

 spiders, in the progress of their growth, cast off* 



