114 MR. CONRAD'S DESCRIPTIONS 



NATICA. 



N. MississippiENSis, PI. 11, fig. 10. — Subglobose, body whorl flattened above; suture channelled; spire 

 little prominent; base profoundly callous ; aperture moderate. Length 8-10. 

 This rare species 1 found about seven or eight miles North West of Vicksburg. 



N. vicKSBURGENSis. PI. 11, fig. 11. — Subglobose, whorls four or five, convex ; umbilicus large ; columella 

 straight ; labium callous. Length 6-10. 



This species is common. 



SCALARIA. 



S. TRiGiNTANARiA. PI. 1 1 , fig. 1 4. — Turreted, whorls convex, cancellated with numerous prominent lines, the 

 longitudinal one lamelloeform and elevated towards the suture, about 32 in number on the body whorl, 

 which is obtusely carinated ; revolving lines equally prominent with the longitudinal, but thicker ' 

 base below the carina with minute revolving lines. Length 9-10. Very rare. 



TURRITELLA. 



T. MISSISSIPPIENSIS. PI. 12, fig. 12. — Subulate, volutions flattened, with seven revolving lines on the larger 

 ones, the penultimate line large and prominent ; longitudinal wrinkles fine, approximate, much 

 curved, crenulating the revolving lines ; the whorls near the apex generally with two prominent distant 

 revolving lines, and a less prominent one margins the suture. Length 3 inches. Not abundant. 



T. ciELATURA. PL 14, fig. 16. — Slightly turreted; whorls flattened, with crenulated or beaded revolving 

 lines, about five to each volution ; lines of growth sinuous and apparently forming the crenulated 

 character of the stri® ; suture profound. 



Rare, and in fragments. 



TEREBRA. 



T. DivisuRUM. PI. 11, fig. 13. — Subulate, with nineteen flattened volutions, obscurely turreted ; polished 

 and with longitudinal curved ribs, dislocated by an impressed line above the middle of each whorl ; ribs 

 obsolete on the body whorl below the impressed line. Length 2 inches. Common. 



The ribs are sometimes obsolete on the larger whorls, or replaced by coarse 

 wrinkles, which are generally distinct on the body whorl. 



T. TANTULA, PI. 11. fig. 15. — Subulate, with longitudinal ribs dislocated by an impressed line; whorls 

 with minute revolving lines. Length |. Rare. 



Very similar to the preceding, but narrower, far less in size, and distinguished by 



the revolving lines and by the ribs on the body whorl, which extend to the beak. 



PLEUROTOMA. 



p. PORCELLANA. PI. 11. fig. 16. — Fusiform ; smooth and polished ; whorls eleven, convex, with two re- 

 volving lines near the upper margin ; the interstices transversely striated ; body whorl with revolving 

 impressed lines, commencing near the upper angle of the aperture ; volution contiguous to the apex 

 papillated ; labium striated ; aperture rather more than half the length of the shell ; beak perfectly 

 straight. Length 1|. 



This shell may perhaps appertain to Brachytoma, Swainson. 



