METAZOA CRUSTACEA. 357 



opposite each other; the other teeth are minute and can 

 be of little use. The eye-stalks are long and prominent 

 and when the animal is alarmed it withdraws them into 

 deep sockets. 



Pseudothelphusa dentata Latr. (No. 874), looks brown 

 and hardy as if it were accustomed to weathering storms. 

 The cephalothorax is nearly triangular in form, with a 

 broad, straight front, tapering posteriorly towards the ab- 

 domen. The first segment of this region is narrow and is 

 Hanked on either side by the basal joint of the fifth pair 

 of legs, but the remaining segments in the female broaden 

 out for use in the breeding season. The arms are for- 

 midable looking organs and in this case the left arm is 

 larger than the right. The abdomen in the walking crabs 

 is bent under the cephalothorax, as we have already seen, 

 and therefore cannot be used as a locomotor organ. It 

 is, in fact, of little use excepting in the female, where it 

 serves as a cover for the eggs which are fastened to its 

 appendages. We should expect, therefore, to find this 

 part in the female much more developed than in the 

 male, and this is the case, as shown by Grapsus macu- 

 latus Catesby (No. 875). 



The cephalothorax of this crab is unusually flattened ; 

 it approaches a circular form excepting in front where it 

 is truncated. All the parts are clearly seen in No. 876, 

 which is a dissection to show the exoskeleton. The 

 seven segments of the abdomen are unusually large and 

 the four pairs of hairy appendages are of considerable 

 size. In this crab the three hinder pairs of walking-legs 

 are the largest, while the se<x>nd pair is comparatively 

 small and the arms are short and stout. The six pairs of 

 mouth parts are similar to those of most crabs, but the 

 antennae are extremely minute and the eye-stalks are 

 short. The sternal portion of the cephalothorax with the 

 genital openings on the third segment are seen in the 

 preparation. The front portion of this region of the body 

 bends vertically downward, giving the truncated appear- 



