40 Charles GELDERD 



Nyctiphanes couchii. 



None of the typical pièces of our type are wanting in this species, 

 although considérable variations of structure are found. 



The cardiac chamber with the latéral pièces S, are considerably elon- 

 gated in the horizontal direction, fig. 41. 



The plates S, are very rich in sharp spines; they carry teeth but he 

 saw-like teeth are wanting. 



What is especially remarkable in this species in the great develop- 

 ment of the longitudinal ridge c, fig. 41, 42. 



The terminal portion assumes a great development, becoming free 

 and projecting as an indépendant pièce over the anterior end of the pyloric 

 chamber, where it no doubt plays an important part in the masticating 

 apparatus of the stomach, fig. 41, 42, c. 



In the cardiac chamber the sumrnit of the ridge is covered with hairs; 

 at the terminal end thèse hairs in the médian line are no longer seen; at 

 each side of the upper surface of the free ridge long hairs are inserted, 

 directed obliquely towards the intestine, fig. 42. 



The ordinary latéral grooves are found at each side of the ridge in the 

 cardiac chamber and the typical line of hairs which are carried by the 

 lower borders of the plates 5, seem especially in this species to hâve the 

 function of a filter or sieve through which fine particles of food pass into 

 the latéral grooves and are carried forward towards the pyloric chamber. 

 The latéral plates S^ are attached to the external integument by sets of 

 very strong muscle bands. 



In Nyctiphanes the V-shaped superior médian pièce p. s. m. is not 

 found. 



It is represented by a pair of latéral cuticular reliefs bearing very fine 

 hairs, fig. 42, p. s. m. 



When the terminal portion of the ridge c becomes free it assumes a 

 blade-like form with convex upper and lower surfaces, fig. 42, c. 



It is inserted exactly between the latéral pièces, 5, and bi\. 



The upper fold br, is not found, the upper surface of the latéral plates 

 5,, still armed with spines being carried on over the anterior portion of the 

 pyloric chamber till it joins the folds S,s, fig. 41, 42. 



The two chambers of the stomach in this région are separated from 

 one another by the blade-like continuation of the ridge c. 



