Crossocephalus from the Rhinoceros. 



95 



tooth at its free end. The jaws are arranged in three pairs, 

 with the bristles of each pair turned towards each other. 

 Between the pairs of jaws there are very slightly raised 

 papillae (fig. 1, P.). The jaws may either be everted and 

 project forward, as in the figure, or they may be completely 

 inverted into the buccal end of the oesophagus, in which case 

 the teeth point backwards, and the rows of bristles meet in 

 the middle of the lumen. Behind the head there is a cuticular 

 collar, bearing on each side a very large forwardly curved 

 papilla (fig. 1, C.P.). When the jaws are inverted these 

 papillae project in front of the head like a pair of horns or 

 ears. No second pair of " neck-papilloa " corresponding to 

 those of G. viviparus has been detected. 



Fig. 1. 



C.P. 



O-l mm. 



Crossoceirfialus longicaudatus. The head, showing the jaws in the everted 

 position ; dorsal view, highly magnified. 



C.P., ear-like papilla on the cuticular collar; J., jaw ; P., oral papilla. 



The oesophagus is about 1 mm. long, and expands into a 

 bulb before opening into the intestine. 



The excretory pore is situated at about 2 mm. (slightly less 

 in the male) from the anterior end. It is in the form of a 

 long transverse slit on the ventral surface, having its lips 

 enclosed within an oval border of radiating cuticular ridges, 

 as has been described and figured by Gedoelst (1916) in the 

 case of the type-species. 



In the male the tail (fig. 2) is 025-03 mm. long, and has 

 a fairly well-marked ventral flexure. There are no alae. 

 The spicules (fig. 2, S.) are unequal in length, measuring 



