ASCARIS DECIPIENS. 



115 



Oar examination of the oesophagus of the Bering Sea form gives the same results 

 which Jagerskiold obtained in studying parasites of the same species taken from 

 Halichoerus grypus. Figs. 16, 17 bring out this point very clearly, so that it is scarcely 

 necessary to repeat the description, although it may be remarked that the intestinal 

 caecum may be long or short, in some cases so short as to appear almost absent, 

 while it is usually concave on the surface which rests upon the oesophagus. • 



The adult males (fig. 9) vary from 33 to 63""" in length by 1 to 1.5™'° in diameter; 

 the body is slightly more attenuated toward the anterior than toward the posterior 

 extremity; the latter (flg. 18) is curled ventrally; it appears somewhat flattened 



Kg. 14. 



Fig. 13. 



dorso- ventrally, and upon closer rtudy is seen to possess a rounded keel-like dorsal 

 ridge, with lateral alae which are curled ventrally, giving the ventral surface a 

 concave spoon-like appearance. Numerous caudal papillae (figs. 18, 19) are present. 

 The six pairs of postanal papillae (flg. 19) are divided into two groups; 1, 2, and 3 are 

 nearer the tip of the conical tail and increase in size so that 2 is larger than 1, and 3 

 larger than 2; occasionally one or another of these papillae are absent; 4, 5, and 6 are 

 nearer the cloaca, and of these 5 is larger than 4 or 6. The praeanal papillae are 

 arranged in a single or doable row eacsh side, and increase in size from the cloaca to. a 

 short distance in front (about praeanal Ifo. 7 or 8), the papillae farther forward being 

 slightly smaller. The spicules are nearly equal in size, 1.5™'" long. 



