136 



THE PUR SEALS OF THE PRIBILOF ISLANDS. 



These specimens, which we have determined as A. typica, represent various stages 

 of development, from young worms 10"™ long by 0.27'"'" broad to fully grown worms 

 44mm long ijy. 2mm broad. 



The head of a female specimen examined measures 0.288"™ broad, and 0.112""° 

 long. The base of the dorsal lip measured 0.2™™ broad by 88 /i long, while its anterior 

 projection measured only 64 /< broad by48/^ long (compare figs. 41, 43); the denti- 

 gerous ridge of the dorsal lip located on the inner surface of this dorsal prolongation) 

 as was iigured by Krabbe. 



Our observations also agree with those of Krabbe, in that we find the anterior 

 margin (figs. 41, 43) of the median projection indented in the median line, thus 

 forming two lobes, and at this point a prominent tooth is occasionally noticed. The 

 parenchyma forms an anterior lobulate branch into each side of the projection. The 

 basal portion is divided into two lateral rounded lobes, near the antero lateral margin 

 of which a round papiUa is plainly visible. Drasche states that the lateral lobes also 



fig. 48. 



bear a dentigerous ridge. This we have not been able to verify, although on the margin 

 of the lobes we noticed a structure which might be interjireted as a dentigerous ridge, 

 but which appeared to us more like a striation. 



The ventro-lateral lips do not, upon first examination, show the distinct division 

 into a prominent anterior narrower and a basal broader portion, such as is described 

 for the dorsal lip; lipon careful investigation, however, and especially upon isolation 

 of the cuticle, a bilobed anterior projection may be seen extending into the space 

 between the three lips, similar to but broader than the bilobed anterior portion of the 

 dorsal lip; this projection bears a dentigerous ridge; the base of the lip is about 

 0.16™™ broad, and the lip is 0.12™™ thick; ordinarily the ventro-lateral lips appear 

 nearly semicircular but asymmetrical in outline. We have not been able to clearly 

 define any dentigerous ridge on the >ase, but we find a number of striae, which might 

 easily be mistaken for such a ridge. The usual papilla is found on the basal portion 

 of each ventro-lateral lip. Intermediate lips are absent; cervical alae absent. The 

 cervical papillae ar . plainly visible 0.60™™ from the anterior extremity. The cuticle of 

 the body is provided with 32 /^ transverse cuticular bauds, apparently without the finer 



