Canadian Arctic Expedition, 1913-18 



Individuals of this species from the arctic are of considerably larger size 

 than those examined by the writer from hosts of The (ireat Lakes. The fully 

 mature females frequently reach a length of 20 mm. and show a very prominent 

 enlargement of the anterior portion of the body (fig. 0). This enlargement 

 is not of the type commonly occurring in gravid females of other species, involving 

 a practically uniform distention of the body, but is restricted chiefly to tin- 

 dorsal surface thereby giving the individuals a distinctly humped app-aranee. 

 In males this anterior enlargement occurs only rarely (fig. S). The males of 

 this species bear a slight resemblance to those of E. gadi, in that the cement 

 islands are arranged in approximately linear order in the posterior region ol 

 the body, though frequently those near the end of the chain in E. Milr 

 overlap one another. 



In the original description of this species the number of proboscis hooks 

 was limited to sixteen longitudinal rows. The present writer has found indivi- 

 duals in the arctic collections possessing eighteen longitudinal rows of hooks 

 but in all other details agreeing with the description of this species. 



Echinorhynchus coregoni Linkins (in Van Cleave, 1919). 



(Plate II, Figs. 10 and 11). 

 Color: as the preceding species (Johansen's notes). 



SPECIFIC DIAGNOSIS. With the characters of the genus. Males 3 to 5 

 mm. long, with a maximum diameter at about the anterior fourth of the body, 

 0-8 to 1-05 mm. Females 3 to 10 mm. long, with maximum diameter of 6 

 to 1 7 mm. Proboscis cylindrical, carrying twelve to fifteen longitudinal rows 

 of hooks, each with ten or eleven hooks. Hooks not crowded on proboscis. 

 Basal hooks 28 to 53 ju Jong; those on middle of proboscis 65 to 80 /* long; those 

 near anterior tip smaller and weaker than those on middle of proboscis. Ventral 

 hooks slightly larger and stronger than dorsal. Lemnisci not longer than 

 proboscis receptacle. Cement glands of male in a compact mass. Embryos 

 within body cavity of gravid female 51 to 91 /* long by 17 to 20 ju wide, with a 

 slight, approximately globular, prolongation of the middle membrane at each 

 pole. 



RECORDS OF THE OCCURRENCE OF E. COREGONI IX HOSTS OF 



ARCTIC AMERICA. 



In this species the nuclei of the subcuticula are very numerous and are 

 distributed almost uniformly over the extent of the body wall. Each mass of 

 nuclear material is surrounded by a comparatively distinct clear region, many 

 of which have the appearance of belonging to the lacunar system (fig. 11). 

 The writer has found the individuals of this species from arctic hosts to be 

 considerably larger than individuals from the region of The Great Lakes. 



