250 NEW FOSSIL SHELLS 
Sciences; but our shell is much larger, more ponderous, with the apex more twisted, and 
without the spines of the C. costata. I have a number of specimens of each now before 
me, and I find that these characters obtain at all ages. 
C. cornucorim, Pu. 35. Fie. 41. 
C. testi valde elevaté et convead, levi, politd, crassd; apice terminali, valde producto, voluto, superné sub-angulato, 
sinistrorsum deflexo; aperturé parvd, ovatd; cyatho profundo, plano, acie curvo. ; 
Shell much elevated, very convex, smooth, polished, thick; apex terminal, very much produced, whorled, some- 
what angular above, turned to the left; aperture small, ovate; cyathus deep, flat, with the margin curved. 
Height .16. Length .30. Breadth .18 of an inch. 
Remarks.—The apex is very far removed from the margin of the mouth; it is slightly 
turned to the left, and has about half a volution. The aperture is ovate, approaching to 
elliptical. ‘The cyathus is situated deep in the shell, so that there is a large cavity under 
the apex. It is perfectly flat, and its outer margin has a gentle and regular incised curve. 
I at first considered this curious little shell as identical with the C. convexa, Say, but 
the differences in the apex and cyathus render the separation necessary. 
C. tamina, Pr. 35. Fig. 42. 
C. testa, discoidale, planissimd, tenui, levi; apice elevato, polito, sinistrorswm defleno, anfractibus sesqui; aperturd 
magnd, subrotundd; cyatho parvo, tenui, convexo. 
Shell discoidal, very flat, thin, smooth; apex elevated, polished, deflected to the left, with a whorl and a, half; 
aperture large, subrotind; cyathus small, thin, convex. 
Height .03. Length .18, Breadth .15 of an inch. 
Remarks.—The most peculiar character in the species now before us, is in the shape 
of the apex. ‘This is perfectly smooth and polished, rising suddenly from the flat back 
of the shell, and twisted into about a whorl and a half. The margin of the mouth 
projects anteriorly beyond it, so that it is invisible on a front view. ‘There are small 
concentric lines of growth over the surface of the shell. The cyathus is slightly and 
regularly convex. 
When very young, this species, from the peculiar formation of the apex, has a striking 
resemblance to a small Natica, and I have been for some time in doubt as to what genus 
a Specimen of that age belonged. 
This shell is closely allied to the C. plana, Say, but the peculiar apex and nearly flat 
cyathus at once distinguish it. 
FAMILY BULL/ALIDA. 
GENUS BULLA. 
B. cyiinprus, Pr. 35. Fra. 43. 
B. testa sub-ellipticd, superne et inferné acuminata, crassd, politd, striata; spird umbilicatd; anfractu ultimo ad 
basim et apicem striato; apertura falcata, inferne lata; columelld reflecta. 
Shell subelliptical, acuminate above and below, thick, polished, striate; spire umbilicate; last whorl striate at the 
base and apex; mouth falcate, wide below; columella reflected, 
