274 NEW FOSSIL SHELLS FROM THE TERTIARY OF VIRGINIA. 



M. EXILIS, PL. 37. FIG. 103. 



M. testa acuminato-cllipticd, comprcssd, tenui, Icevi, politd; spird attenuatd, obtusd, ovatd; suturis obsoletis; anfractibus , 



planis; anfractu ultimo rotundato; basi Icevi, acuminatd; aperturd angustd, ovatd; columelld plicis quatuor; labro acuto, intus 

 costd longitudinali. 



Shell acuminately elliptical, compressed, thin, smooth, polished; spire attenuate, ovate, obtuse; sutures obsolete ; 



whorls , flat; last whorl rounded; base smooth, acuminate; mouth narrow, ovate; columella with four folds; 



outer lip acute, with a longitudinal costa within. 



Length .18. Breadth .10 of an inch. 



Remarks. The spire is covered with a smooth porcelain-like deposite, which oblite- 

 rates the sutures, and renders it impossible to determine the number of whorls. The 

 most peculiar character about this shell is the internal rib, near the edge of the outer lip, 



FAMILY CONVOLUTION. 



GENUS OLIVA. 



O. CANALICULATA, PL. 37. FlG. 104. 



0. testa cylindraced, crassd, Icevi, nitidd; spird exsertd, obtusd, scalariformi; anfractibus quinque, angulatis, prope suturam 

 infcriorem incrassatis; suturis valde profundis, latis, canaliculatis; basi acuminatd, striis raris, parvis, transversis; aperturd 

 lineari, superne valde incisd, inferne emarginatd; columelld multiplicatd; labro acuto. 



Shell cylindrical, thick, smooth, shining; spire exserted, obtuse, scalariform; whorls five, angular, incrassated near 

 the lower suture; sutures very deep, wide, canaliculate; base acuminate, with a few small transverse strise; mouth 

 linear, deeply incised above, emarginate below; columella with many folds; outer lip acute. 



Length 1.60. Breadth .70 of an inch. 



Remarks. The line of incrassation on the lower part of the whorls, is wanting on the 

 last one. To those of the spire, it gives a peculiar bullate appearance. The sutures are 

 larger and deeper than in any other of the genus. The outer lip is attached to the body 

 of the shell only by a small transverse plate, near its upper extremity, which causes the 

 peculiar suture. This plate does not extend to the edge of the lip. ^ 



There is a specimen of this shell, without a name, in the collection of the Academy of 

 Natural Sciences of Philadelphia. I am surprised that it has not been heretofore de- 

 scribed, as it is a remarkable shell and by no means rare. It has hitherto, I believe, 

 been confounded with one of our recent species, which it distantly resembles. 



0. ANCILLARLEFORMIS, PL. 37. FlG. 105. 



0. testa ovato-cylindraccd, tenui, Icevi, politd; spird subulatd; suturis canaliculatis; anfractibus , planis; anfractu ultimo 



rotundato; basi Icevi; aperturd sub-triangulari, effusd, minime incisd; columelld striis nullis, inferne varied parvo; labro acuto. 



Shell ovate-cylindrical, thin, smooth, polished; spire subulate: sutures canaliculate; whorls , flat; last whorl 



rounded; base smooth; mouth sub-triangular, effuse, very slightly incised; columella with no striae, a small varix 

 below; outer lip acute. 



Length .25. Breadth .10 of an inch. 



Remarks. On one of my specimens there is a deep narrow groove immediately below 

 the upper suture. As it exists only on this specimen, and there but at intervals, I sup- 

 pose it to be merely a fortuitous character. The mouth is acutely angular above and 

 wide below. 



The peculiar conformation of the columella and base of the mouth seem to place this 

 shell among the Ancillarise, but its sutures and naked spire separate it from that genus. 



