186 BULLETIN OF THE 



but not channelled suture ; sculpture of (on the last whorl about fourteen) 

 stout rounded ribs with wider interspaces, completely crossing the whorls, and 

 fine incremental striae; spiral sculpture of (on the last whorl about ten) re- 

 volving ridges, faint in the interspaces, strongly ovally noduled on the ribs, 

 three rows showing on the upper whorls; ribs interlocking at the sutures; 

 aperture rounded, with its edge continuous and raised, contracted in front of 

 a stout varix, Urate on both sides, a stout tooth on the body and another at the 

 base of the pillar; a deep groove behind the siptional fasciole; canal short, 

 strongly twisted. Operculum serrate at the sides. Lon. of shell, 12.0; of last 

 whorl, 8.0; of aperture, 5.0. ; max. lat. of shell, 7.5 mm. 



Habitat. Station 272, at Barbados, in 76 fins.; Station 132, near Santa Cruz, 

 in 115 fins., rocky bottom, temperature 65°. F. (living); Station 2, in 805 

 fms. ; Station 206, near Martinique, in 170 fins.; Station 220, off Santa Lucia, 

 in 116 fms., rocky bottom, bottom temperature 58°.5 F. 



Nassa scissurata var. pernitida Dall. 



Shell more slender and elongated, spiral sculpture weaker, hardly nodu- 

 lating the ribs; ribs becoming obsolete on the last whorl. Lon. 16.5; max. 

 lat. 7.5 mm. 



Habitat. Station 299, near Barbados, in 140 fms. 



This species is clearly distinguished from N. Hotessieri, which is its nearest 

 relative, by the character of the sutures which are not channelled, by its fewer 

 strongly nodulated ribs, and by the curve of the ribs, which in Hotessieri, as in 

 most ribbed univalves, are convex forward on the periphery and then curve 

 a little backward, while in N. scissurata the curve is in a contrary sense, as is 

 at once evident on comparing two specimens. The total curve is not great, 

 but quite sufficient to form a marked distinction. 



This species has the bright waxen lustre of a deep-water shell, and probably 

 lives in between 75 and 200 fms. depth. Its sculpture recalls that of N. spi- 

 nulosa Phil. 



Family COLUMBELLID^. 

 Genus COLU3IBELLA Lamarck. 



Of the genuine typical Columbellas there are two abundant species in this re- 

 gion, C. mercatoria Lamarck and C. rustica Linne. The Antillean and Floridian 

 specimens of the latter, though probably conspccific, have a markedly different 

 facies from the Mediterranean variety, and have been called rusticoides by 

 Heilprin in a recent paper on the Pliocene of the Caloosahatchie beds of South 

 Florida. C. rustica is found in these beds precisely like the recent Florida 

 form, for which it may be well to retain Heilprin's name in a varietal sense. 



Most of the other species can be referred to one of five subgenera or sections 



