FROM THE TERTIARY OF VIRGINIA. 25 



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.E. 



GENUS PASITHEA, (LEA.) 

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



P. testa subulatd, acuminatd, crassd, imperforatd, nitente, costata; spird valde atlenuala, mamillata, ad apicem letvi: 

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

 fraclu ultimo angulato; bast laoi, politd; aperturd parvd, sub-quadratd, sub-effusa. 



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

 apex, sutures deep, excavated; whorls fifteen, flattened, with numerous fiat 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. STJBULA, PL. 35. FIG. 45. 



P. testa subulata, crassd, imperforatd, costata, striata; spird attenuatd, obtusd, mamillata, ad apicem polita; suturis 

 profundis; anfractibus oclo, contexts; costis longitudinalibus magnis, crebris, prope basim obsoletis, planulatis, Ics- 

 vibus; striis transversis, parvis, crebris, interruptis; ultimo anfractu rotundato; basi l<evi; aperturd arctatd, ellipticd, 

 sulieffusa. 



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

 deep; whorls eight, convex; costse 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 marnelon. 

 The transverse striae are very small and do not cross the costfe. 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 subulata, elongatd, tenui, politd, sub-perforatd. costatti, striata; spird attenuatd, mamillatti. conicd; suluris 

 linearibus, imprtssis; anfractibus duoJecim, sub-convexis; cottis longitudinalibus, magnis, plants, lavibus; prope 

 suturam superiorem striis transversalibus parvis, crebris; prope suturam inferinrem striis transversalibus magnis. 

 raris; anfractu ultimo rotundato; basi striata; pe'foratione pene obsoletd; aperturd ovatd. 



