FROM TftE TERTIARY OF VIRGINIA. 253 



; Shell ovately elongate, acuminate, thin, sub-perforate, diaphanous, striate; spire somewhat attenuate, mamillate; 

 sutures impressed, linear; whorls six, convex; striae transverse, minute; last whorl rounded; base striate; mouth 

 elongately-quadrate, sub-effuse. 



Length .22. Breadth .10 of an inch. 



Remarks. The strise are very small and only to be seen with the aid of a microscope. 

 The shell is very thin, so much so as to be somewhat translucent. The mouth is 

 angular above and below. There is a slight angle on the superior part of the whorls, 

 immediately below the upper suture. 



This pretty little shell has no decided resemblance to any of our fossil species. P. 

 sulcata, Lea, approaches it more nearly than any other. 



P. TIJRBINOPSIS, PL. 35. FIG. 50. 



P. testa ovato-conoided, sub-elevatdj tenui, Icevi, imperforatd; spird breviuscula, rotundatd, obtusd; suturis pro* 

 fundis ; anfractibus quatuor, convexisj prope suturam superiorem sub-canaliculatis ; anfractu ultimo rotundato; basi 

 ItBvi; aperturd magnd, sub-rotunda. 



Shell ovately conoidal, somewhat elevated, thin, smooth, imperforate; spire rather short, rounded, obtuse; sutures 

 deep; whorls four, convex, sub-canaliculate near the upper suture; last whorl rounded; base smooth; mouth large, 

 sub-rotund. 



Length .10. Breadth .05 of an inch. 



Remarks. The whorls have a small angle immediately at the upper suture, which 

 gives them somewhat the appearance of being channelled. The mouth is oblique, 

 nearly round, and has the lower margin produced obliquely, below the inner lip. 



I have felt some doubts in placing this shell among the Pasithese, as it hardly has 

 the effuse mouth of that genus, but its characters seem to agree better with it than Avith 

 any other. 



This little shell resembles some of our recent species of Amnicola; it also approaches 

 the Turbo minutus, Totten (Gingula minuta, Gould,) but it is more globose and differs 

 in size. 



P. ORNATA. 



P. testd ovato-subulatd, crassd, sub*perfordtd } costatd, striatd; spird elevatd, mamillatd, prope apicem Itevi; suturis 

 linearibus-; anfractibus quinque, valde convexis; costis transversalibus, latis, politis; striis longitudinalibus^ minu- 

 tissimis; anfractu ultimo rotundato; basi costulatd; perforatione pene obsoletd; aperturd ovatd, effusa. 



Shell ovately subulate, thick, sub-perforate, costate, striate; spire elevated, mamillate, smooth near the apex; su- 

 tures linear; whorls five, very convex; costee transverse, wide, polished; striae longitudinal, very minute; last whorl 

 rounded; base costulate; perforation almost obsolete; mouth ovate, effuse. 



Length Breadth -> 



Remarks. On the upper whorls the costse are five in number, on the last one they are 

 much more numerous. Those on the base are smaller and closer together. Near the 

 lower sutures, on the whorl next the last, is a rib larger than the rest, with an impressed 

 line in its centre, making a kind of double rib. It may be traced round the middle of 

 the last whorl. As I have but one specimen before me, I cannot decide whether this is 

 a general character of not. The longitudinal striae are only to be seen in the intervals 

 of the ribs. They are very small and sometimes disappear.* 



* I unfortunately lost my only specimen of this shell after describing, but before measuring or making a drawing 

 of it. I am, therefore, unable to give either the dimensions or a figure. It was, however, not more than a quarter 

 of an inch in length, at the utmost. 



VOL. ix. 67 



