22 



obtusely fusiform ; suture distinct ; whorls six, obsoletely wrin- 

 kled ; aperture longitudinally subovate ; exterior lip reflected, but 

 not flattened, interrupted above by the penultimate whorl, and 

 with five teeth, of which the superior one, and that which precedes 

 the basal one, are smallest ; labrum with an undulated lamelliform 

 tooth, its anterior extremity little elevated, but elongated so as 

 almost to join the superior extremity of the exterior lip. 



Length three-twentieths of an inch. Inhabits Upper Missouri. 



Var. a. — The two smaller teeth obsolete or wanting. Var. b. — 

 The basal tooth obsolete or wanting. 



Very distinct from corticaria, it being a much larger and pro- 

 portionally more dilated shell ; and with that species and the next 

 seems to belong more properly to the genus carychium of Muller 

 and Ferussac. 



P. RUPicoLA. — Shell dextral, attenuated to an obtuse apex, 

 white ; whorls six, glabroiis ; suture deeply impressed ; labrum 

 bidentate ; superior tooth lamiform, emarginate in the middle, and 

 at the anterior tip obtusely uniting with the superior termination of 

 the labium ; inferior tooth placed upon the columella, and extend- 

 ing nearly at a right angle with the preceding ; labrum tridentate, 

 teeth placed somewhat alternately with those of the labium, infe- 

 rior tooth situated at the base and immediately beneath the inferior 

 tooth of the labium. 



Length about one-tenth of an inch. Inhabits East Florida. 



I formerly found it abundant on the banks of St. John River, 

 in East Florida, and more particularly under the ruins of Fort 

 Picolata, under stones, &c. 



It is about the size of P. corticaria, and considerably resembles 

 that species, but is sufficiently distinguished by the circumstance 

 of its gradually decreasing in diameter from the body whorl, to its 

 obtuse tip ; and, in the character of the mouth, it is widely dis- 

 tinct. 



SucoiNEA ovALis. — (Jour. Acad. Nat. Sc. vol. i. p. 15.) A 

 large variety of this species is found very common on the Missouri, 

 of the length of about four-fifths of an inch ; I observed one speci- 

 men which was upwards of an inch long. 



Cyclostoma MARGiNATA. — Shell turreted, pale horn color, or 

 dusky, obsoletely wrinkled across ; suture rather deeply impressed ; 

 volutions six ; aperture mutic, suboval, truncated transversely 



