264 BULLETIN OF THE 



Bivonia ? exserta Dall. 



Plate XXVI. Fig 6. 



Bivonia exserta Dall, Bull. M. C. Z., IX. p. 39, 1881. 



Habitat. Station 20, 220 fms. Off Cape San Antonio, in 1002 fma. Bar- 

 bados, 100 fms. Off Cape Lookout, N. C, in 31 fms., sand, U. S. Fish 

 Commission. 



The figured type is young. The Fish Commission specimen shows that, 

 after the portion annulated like the figure is complete, the sculpture changes; 

 the dorsal carina becomes prominent and notched like the upper edge of an 

 alligator's tail, and projects forward like a spine over the aperture. The rest 

 of the shell loses its sculpture, except incremental lines, the lateral carina 

 disappear, but are represented by short spines at the aperture. The shell is 

 of a greenish white. 



Family TURRITELLIDiE. 

 Genus TURRITELLA Lamarck. 



Section TORCULA Gray. 



This group is composed of species which have the appearance of the tips of 

 Vermicularia before the latter begins to go astray. But the more timid Tor- 

 cula never gets its courage up to the point of departure into devious ways. 

 They are readily distinguished by the excavated appearance of the base and 

 the sinuous outer lip. There are three species on the southern coast of the 

 United States. One is very slender, nearly smooth, and much drawn out. I 

 have never seen more than fragments of it, which came from the coast of Texas 

 and of North Carolina, in 40-50 fms. The others follow in their order. 



Turritella (Torcula) exoleta Linne. 

 Turritella exoleta Linne', Syst. Nat., ed. x., No. 561. Tryon, Man., VIII. p. 205, 1886. 



Habitat. West of Florida, in 50 fms. ; off Havana, in 80 fms. ; off Sombrero, 

 in 54 fms.; Station 152, in 122 fms., off St. Kitts; Station 247, in 170 fms., 

 near Grenada. Coast of Texas and the Florida Keys, 45-80 fms., U. S. Nat. 

 Museum. 



This pretty species is rather variable in sculpture at different ages and in 

 different individuals. The apical angle varies slightly, some specimens being 

 more slender than others. The nucleus is dextral and sculptured. 



Turritella (Torcula) acropora n. s. 



Nucleus white, polished, loosely coiled, small, with about two very rounded 

 whorls. Shell whitish, violet, or pale rose-color, with longitudinal flaramules 



