MONOGEAPH OF THE GENUS PEEIPATUS. 459 



Fig. 20 shows very clearly the peculiar collapsable joints which 

 this appendage possesses in all the species. 



The buccal cavity, tongue, and lips resemble in all 

 respects the same structures in the South African species. 



The jaws differ from those of the latter only in being 

 without the small tooth on the outer blade. 



The ambulatory appendages (fig. 21) are fifteen in 

 number in all the specimens which I have examined. They 

 resemble in their general features the same structures in 

 Capensis, so that in the following short description stress 

 will be laid only on the points in which they differ from the 

 latter. 



The opening of the segmental organ at the base of the leg is 

 much more indistinct than in C a p e n s i s, and the peculiar tumid 

 papillae, which in Capensis extends from its outer border on 

 to the ventral surface of the leg, are absent in this species. 

 There are three pads, but the large papillae of the row adjoin- 

 ing the proximal pad are larger with regard to the ordinary 

 papillae than in Capensis. Sometimes, indeed, they are so 

 large as to present the appearance, unless closely examined, of 

 one continuous spinous pad. 



The foot differs from that of Capensis in the following 

 points. The two prominent papilla?, placed one on each 

 side (anterior and posterior) of the base of the foot are 

 absent. The dorsal side of the foot near the free extremity 

 possesses a papilla (fig. 21a), while the anterior face bears, 

 like the posterior, only one papilla. As in Capensis, 

 the opening of the nephridia of the fourth and fifth legs 

 are placed on a small portion of the proximal pad. The 

 part of the pad around the opening is only partly separated 

 from the rest (vide fig. 21). The fifteenth leg, so far as I 

 could ascertain, differs only in size (being slightly smaller) 

 from the preceding, and is without the white papilla found on 

 the last leg of the male of the South African species. Anal 

 papillae are never present. 



Internal Anatomy. — As already explained, I do not 

 propose to give in the monograph any detailed account of 



