50 



U.S. NATIONAL MUSEUM BULLETIN 2 78 



7.0 



8.0 9.0 10.0 11.0 12-0 13.0 U-O 15-0 16-0 17-0 18.0 19.0 



Figure 22. — Ratio of total length divided by length of basis of gnathopod 2; a, Caprella 

 septentrionalis, males, n = 47; b, C. septentrionalis, variant males, n=10; c, C. septentrio- 

 nalis, females, n^42; d, C. linearis, females, n=16; e, C. linearis, males, n = 34. Vertical 

 line represents the range, horizontal line the mean, stippled area two standard errors 

 either side of the mean, and white rectangle one standard deviation either side of the 

 mean. 



Variation. — The body of this species varies in the amount of 

 spination, larger individuals tending to be less spinose (compare figs. 

 23c, 24a, 24b). The peduncle of antenna 1 shows some variability in 

 the density of setules; larger males tend to develop more setules. 



Distribution.— Type-locality: Albatross sta. 2253, 40°34'30" N., 

 69°50'45" W., 59 m. 



Other records: Southeastern New England, Long Island Sound, 

 Vineyard Sound, Great Harbor in Woods Hole, passage between Vine- 

 yard Sound and Buzzards Bay, Cape Cod Canal; 0.3 to 25 m. 



New records: St. John's, Newfoundland; Casco Bay, Maine; off 

 Cape Cod, 40°-43° N., 65°-72° W.; 37°31' N., 74°52' W. 



Remarks. — Wigley and Shave (1966) give an excellent description 

 of C. grahami which they thought to be distinct from C. unica due 

 to the presence of spines on the dorsal surface of the latter species. 

 Mayer based his description of C. unica upon a single immature male 

 which was quite spiny; however, recent material collected from the 

 area near the type-locality has yielded numerous specimens which 

 intergrade between the smooth and spiny forms. Since the other 

 characters of these two species agree quite closely and intergrades 

 are present between the two body forms, C. grahami is suppressed 

 as a junior synonym of C. unica. 



