^ 



ARAOHNIDA. 2ij3 



front, which is termed the Cephalo- thorax, contains 

 the organs of sensation, and of mastication, and 

 also the principal reservoir of circulating fluids ; 

 the other, which is behind, and contains the organs 

 of digestion, is termed the abdomen. In the spider 



(Fig. 1.36, 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 ce- 

 phalo-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 suc- 

 ceeding 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 prehen- 

 sion, 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 their outer skin 

 several times, and at regular periods. In the earlier 



