118 



THE FUR SEALS OF THE PRIBILOF ISLANDS. 



characteristic lips were tlieii visible. A small, conical spine, about 20 // long, is also 

 prfesent on the tip of the tail; this spine is finely striated tranversely and is curved 

 ventrally or dorsally. Of internal organs, the intestinal tract is well developed; the 

 oesojjhagus is divided into an anterior i^ortion about 1.8'"'" long and a posterior 

 portion about 0.8""" long; in younger specimens (fig. 20) in which the oral tooth was 

 present, the oesophageal and intestinal caeca were absent, but in specimens which 

 had shed the oral tooth the intestinal caecum was present, the intestine aiul rectum 

 were distinct. From lack of time the other internal organs were not studied carefully. 

 Yon Liustow (1878, pp. 237, 238) described a young nematode from the muscles 

 of Onmorus eperlanus under the name Aacaris cpcrlani. These worms measure 23.4'"'" 

 long by 0.72'"'" broad; the oral tooth is absent, but the three lips are jireseut; the 

 intestinal caecum is also present. '■'■ Wematoideum salmonis eperlani liud." is given 



Fifl. 19. 



as a synonym, and Atjamonema hicolor Diesing is mentioned as the embryonic form. 

 Tliis latter worm voii Liustow also found in Osmerus eperlanns; it measured 8.8'"'" 

 long by 0.23'"'" broad, llie oral tooth was present, and the intestiniil caecum was well 

 developed. Later von Liustow (1895, pi». r)iy-524) describes Ascaris cpcrlani more iu 

 detail and suggests that it represents the larval stage of A. sea ris decipiois. Atjamo- 

 nema hicolor was first described as Filaria hicolor ('replin, and isre])ortc(l from " Perca 

 Jlitvicttilis, Accriud rulffurin, O.smcrns eperlanns, Lota co))i munis, and Gasterosleus 

 fluviatiliHj'' 



Von Liustow may be correct in his supposition that the worms known as Agamo- 

 nema hicolor ( Filaria hicolor), Xematoidcum salmonis eperlani and Asearis eperlani 

 represent the younger stages of .4. r7«;t/;ieH.v, in which case the five fish just mentioned 

 would form intermediate hosts, but our experience with the earlier determinations 



