64 AMERICAN MARINE CONCHOLOGY. 



Genus OBELISCUS, Humphrey. 

 Mus. Calonn. 1797. 



1. 0. CRENULATUS, Hglmes. Fig. 110. 



Post Pliocene Foss. So. Car. 88, t. 13, f. 14. I860. 

 Shell subulate, smooth, angularly channelled at the suture, which 

 is crenulated on the lower whorls only ; columella with three folds, 

 the superior one large and acute, the others small; outer lip with 

 four small teeth internally; whorls fourteen to sixteen; with two 

 indistinct opaque revolving bauds, which are sometimes obsolete. 



North and South Carolina. 



Genus TTJREONILLA, Risso. 

 Hist. Nat. Eur. Merid., iv. 224. 1826. 

 Chemnitzia, Orb. Webb and Berthol. Hist. Nat. lies Canaries. 1839. 



1. T. INTERRUPTA, Totten. Fig. 111. 



(Turritella) Am. Journ. Science, xxviii. 352, f. 7. 1834. 

 Shell small and slender, whorls ten, almost flat, on which are 

 twenty to thirty transverse obtuse ribs, crossed by about fourteen 

 subequal revolving lines interrupted by the ribs; these are 

 arranged in pairs, so closely applied as often to be confounded in 

 one; below the middle of the body-whorl, the ribs become obsolete, 

 and the revolving lines are uninterrupted ; a slight shoulder on 

 each whorl causes the sutures to be quite distinct. Aperture 

 ovate, sharply angular above; inner lip slightly everted. Whitish- 

 brown or amber-colored. 



Length 6.25, diam. 2.4 mill. 



Mass, to North Carolina. 



2. T. NIVEA, Stimpson. Fig. 112. 



Proc. Bost. Soc. Nat. Hist., iv. 114. 1851. 



Shell aciculated, sub-cylindrical, white shining ; whorls eleven, 

 flattened, longitudinally plicate ; folds straight, interstices per- 

 fectly smooth. 



Length 7, diam. 1 mill. 



Animal white ; head short ; tentacles triangular, very broad, 

 with the eyes at nearly the middle of their bases ; foot elongated, 

 with an arcuated indentation at its anterior terminus. 



This species differs from T. interrupta in being more slender, in 

 wanting revolving lines, and also totally in its station, tlie deeper 

 parts of the Coralline Zone. Taken in forty fathoms, on a muddy 

 and gravelly bottom. 



Grand Manan Island, Bay of Fundy. 



