FROM THE TERTIARY OF VIRGINIA. 251 



Length .21. Breadth .10 of an inch. 



Remarks. Although this shell has no very peculiar characters, yet I cannot refer it 

 to any described species. One or two species, the B. St. Hillairii and Dekayi, from 

 Claiborne, are somewhat allied to it, but they are not identical. 



FAMILY MELANID^. 



GENUS PASITHEA, (LEA.) 

 P. EXARATA, PL. 35. FIG. 44. 



P. testa subulatdj acuminatd, crassd, imperforatd, nitente, costatd; spird valde attenuatd, mamillatd, ad apicem l&vi; 

 suturis profundis, excavatis; anfractibus quindecim, planulatis, costis oblique longitudinalibus crebris plants; an- 

 fractu ultimo angulato; basi Icevi, politd; aperturd parvd, sub-quadratd, sub-effusd. 



Shell subulate, acuminate, thick, imperforate, shining, costate; spire very attenuate, mamillate, smooth at the 

 apex, sutures deep, excavated; whorls fifteen, flattened, with numerous flat obliquely longitudinal ribs; last whorl 

 angulate; base smooth, polished; mouth small, sub-quadrate, somewhat effuse. 



Length .35. Breadth .07 of an inch. 



Remarks. The ribs are slightly oblique. They disappear at both sutures, which are 

 triangular, smooth and deep. They extend, on the last whorl no farther than the angle, 

 leaving the base perfectly smooth. The mouth is ovately quadrate, with sharp angles 

 where the columella and outer lip join the preceding whorls. 



This shell appears to resemble the Turritella laqueata, Con., but its larger size, mami- 

 late apex, and angular mouth serve to distinguish it from that species. 



P. SUBULA, PL. 35. FIG. 45. 



P. testa subulatd, crassd, imperforatd, costatd, striatd; spird attenuatd, obtusd, mamillatd, ad apicem politd; suturis 

 profundis; anfractibus octo, convexis; costis longitudinalibus magnis, crebris, prope basim obsoletis, planulatis, I<E- 

 vibus; striis transversis. parvis, crebris, interrupts; ultimo anfractu rotundato; basi l&vi; aperturd arctatd, ellipticd, 

 subeffusa. 



Shell subulate, thick, imperforate, costate, striate; spire attenuate, obtuse, mamillate, polished at the apex; sutures 

 deep; whorls eight, convex; costae longitudinal, large, numerous, obsolete near the base, flattened, smooth; striae trans- 

 verse, small, numerous, interrupted; last whorl rounded; base smooth; mouth narrow, elliptical, sub-effuse. 



Length .18. Breadth .05 of an inch. 



Remarks. The costse continue almost to the base, when they disappear suddenly, 

 leaving a small place smooth immediately behind the columella. The first whorl of the 

 spire is round, somewhat twisted, smooth and polished, forming a remarkable mamelon. 

 The transverse stria3 are very small and do not cross the costae. The mouth is slightly 

 angular above, and somewhat effuse at base. 



This shell attains a greater size than that given above. I have several fragments of 

 much larger specimens. 



P. EBURNEA, PL. 35. FIG. 46. 



P. testa subulatd, elongatd. tenui. politd, sub-perforatd , costatd, striatd; spird attenuatd, mamillata, conicd; suluris 

 linearibus, impressis; anfractibus duodecim, sub-convexis; costis longitudinalibus, magnis. planis. lavibus: prope 

 suturam superiorem striis transversalibus parvis, crebris; prope suturam inferiorem striis transversalibus magnis, 

 raris; anfractu ultimo rotundato; basi striatd; perforationc pene obsoletd; aperturd ovatd. 



