MUSEUM OF COMPARATIVE ZOOLOGY. 123 



Nucula tenuis Montague. 

 Nucula tenuis Forbes and Hanley, Brit. Moll., II. 223, PI. 47, f. 6. 



Sigsbee, off Havana, 175 and 450 fins.; off Mono Light, 292 fms.; Station 20, 

 220 fms.; Station 3, 450 fms. 



These specimens agree very well with British and some Arctic specimens of 

 N. tenuis, although the waters in which they live are many degrees warmer 

 and perceptibly Salter than those of the North. 



Nucula crenulata A. Adams. 



Nucula crenulata A. Adams, P. Z. S., 1860, p. 52. Hanley, Mon. Nuculidce, PL IV. 

 figs. 134, 135 (Guadaloupe). 



Twenty miles west of the Florida coast in 30 fms. ; Station 36, 84 fms. ; Bar- 

 bados, 100 fms.; Sigsbee, off Havana, in 158, 182, and 450 fms.; Station 20, 

 220 fms.; Station 19, 310 fms.; Yucatan Strait, 640 fms. Variety obliterata : 

 Station 44, 539 fms.; Yucatan Strait, 640 fms.; Station 2, 805 fms. 



There seems to be little doubt that this is Adams' species, though uniformly 

 more trigonal than Hanley's figure of the same from the unique type. Most 

 of them have very strong sculpture, which is irregular. The teeth are 9 ante- 

 rior, 15 posterior, with a well-marked cartilage pit. In the variety obliterata 

 the shell is higher and still more triangular ; teeth, 8 anterior, 12 posterior ; 

 and the sculpture almost entirely obsolete, the radiating striae least so. 



Nucula cytherea n. s. 



Shell with nearly the outline of Tapes virgineus, as figured by Jeffrevs (Brit. 

 Conch., PL XXXIX. fig. 5), but with the beaks higher and more central and the 

 anterior end more broadly rounded ; color pale straw-color or white, beauti- 

 fully polished, with no radiating sculpture ; concentric sculpture of regular 

 rounded waves, as in Lioctjma, of which there are about forty, finer and closer 

 on the beaks, with a tendency to become obsolete at the anterior basal portion 

 of the shell; shell evenly convex ; beaks well marked, but not prominent ; 

 inner margin not crenulate ; anterior teeth 12-14 ; posterior teeth 25 87, all 

 slender, long, comblike, and not !> -shaped; ligamentary fossette or pit ex- 

 tremely minute, so that the series of teeth is practically continuous. Neither 

 lunule nor escutcheon is visible, nor can they be said to exist in this speciea : 

 interior polished, white, not perceptibly pearly, but having a sort of opaline 

 lustre when viewed in a strong light. Lon, S.6 ; alt. 6.75 ; diam. 5.0 mm. 



Olf Cape San Antonio, 413-424 fms.; Yucatan Strait. 640 fms. 



This species is beautiful and remarkable both in form and sculpture. I have 

 not found any Nucula of this shape figured anywhere or described in modern 

 publications on the recent or fossil species of the group. It would perhaps be 

 referred to the section Tindaria. 





