656 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.41. 



tliree instead of four oblique lateral ridges, of which the tluiTl fads 

 to unite below with the second, wlule the lateral ridge of the pseudo- 

 rostrum does not extend back to the first ; the first legs are distinctly 

 shorter; the carpus of the second legs is more than twice as long as 

 the merus; the postero-lateral angles of the last thoracic somite are 

 strongly produced and spiniform. The male is distinguished from 

 that of I), sculpta (as figured by Sars) by possessing a strong hori- 

 zontal ridge on each side of the carapace, running forward from the 



Fig. 79.— Diastylis polita, female, from the side. 



hind margin. Adult specimens of both sexes are considerably larger 

 (male 14 mm., female 12 mm.) than those of D. sculpta. 



The localities given for the species by Professor Smith extend from 

 the Gulf of St. Lawrence to Vineyard Sound and from the surface to 

 190 fathoms. 



Localities. — U. S. F. C. station 91 (1877) ; off Halifax, Nova Scotia; 

 6i fathoms; bottom temperature, 49° F.; U.S.N.M. 38024; 1 female. 



Fig. 80.— Diastylis polita, male, from the side. 



U. S. F. C. stations 72-73 (1877) ; Halifax Harbor, Nova Scotia; 18 

 fathoms; bottom temperature, 39.5°-41.5° F.; U.S.N.M. 44058; 1 

 female. 



La Have Islands, Nova Scotia; 6 fathoms; in fine mud; Geol. Surv. 

 of Canada, Aug. 7, 1910; U.SN.M. 44062; 7 females. 



U. S. F. C. station 141 (1878); Gloucester Harbor; 8^ fathoms; 

 bottom temperature, 44.5° F.; U.S.N.M. 36647, 36648, 44061; many, 

 male and female. 



U. S. F. C. station 145 (1878); Gloucester Harbor; 8 fathoms; 

 bottom temperature, 51° F.; U.S.N.M. 36640, 36643, 44155; many, 

 male and female. 



