48 U.S. NATIONAL MUSEUM BULLETIN 278 



The ratio of the total length to the length of the basis of gnathopod 

 2 varies slightly as illustrated in figure 22. 



Distribution. — ^Type-locality: "It seems to be common in 

 the Greenland seas***, but is not mentioned by Sabine and 

 Ross**** • . . .***Sydproven, Julianchaab, Fiskenaesset, Godthaab and 

 Nenertalik are those places from which it has been sent." (Translated 

 from Kr0yer, 1838) 



Other records: Murman coast; Novaya Zemlya; White Sea; N. 

 Russia; Norway to France and British Islands; Faeroe Islands; Jan 

 Mayen; Iceland; East and West Greenland; BafiBn Bay and Davis 

 Straits; coast of North America from Hudson Bay to Maine. 



New records: Many localities south to Georges Bank. 



Remarks. — This species occupies almost the same habitat as C. 

 linearis. It has been taken in the stomachs of the pollock Pollachius 

 (Scott, 1901) and the rock cod Gadus (Johansen, 1925). It ranges in 

 depth from the surface to 1026 m. 



As evidenced by the long synonymy, this species exhibits a variety 

 of body forms. Mayer (1890, 1903) viewed these forms as variants 

 of the same species; however, Stephensen (1928, 1940) treated several 

 of these forms as distinct species or subspecies. The material available 

 to me of this species is quite large and intergradations between the 

 forms are numerous. No geographical isolation of these forms is 

 evident and therefore they probably represent only infrasubspecific 

 variants. Perhaps ecological data would reveal some other type of 

 isolating mechanism, but type of datum is not available to me. 



Figure 21 is a variant of this species, which was collected in Casco 

 Bay, Maine. It corresponds to G. Sar's (1895) concept of C. monocera 

 and to Mayer's C. septentrionalis f. longicornis. In common with C. 

 linearis it bears numerous setules on the peduncle of antenna 1 and 

 has elongated pereonites 1 and 2. Since the females of C. linearis and 

 C. septentrionalis are frequently indistinguishable and the gnathopods 

 are quite similar, this variant caused concern over the distinctiveness 

 of these species because it might represent a hybrid. In figure 22 the 

 ratio of the total length to the length of the basis of gnathopod 2 

 is plotted. The variant and males and females of C. septentrionalis 

 are not significantly different in this character; however, they are 

 significantly different from both the males and females of C. linearis. 

 Relying on this character, the females of the two species can be 

 separated and it justifies the inclusion of the variant within C. sep- 

 tentrionalis. The problem of the possible species distinctiveness of 

 Mayer's varieties and Stephensen's species and svibspecies is still 

 unresolved, and its solution will probably not be found until ecologic 

 and genetic studies can be carried out. 



