New LameUihranchiata. — TJlrich. 99 
closely incurved beaks. Anterior macular impression, as seen in 
casts of the interior, scarcely visible in a side view, being over- 
hung by the side of the umlio. In an end view they api)ear like 
two narrow vertical lobes tapering upward and placed just be- 
neath the free portion of the beaks. The surface of casts is full 
and rounded. 
If Tanvxemla Billings, is to be retained for species of this 
genus having the beaks subterminal, then not only the present 
but most of the associated species will have to go there. Of the 
latter C rectirostris Hall, which is exceedingly like T". tuconstans 
Billings, is the most abundant and perhaps the nearest to C. 
terminally, still, the two species are widely different, that one 
having a strong and thick shell, on the innej' side of which there 
is, as in many other species of the genus, a ridge-like thickening 
that gives rise to the distinct sulcus and flattening of the beaks 
on internal casts. In C. terminal !>< on the contrary the shell is 
thin and without the internal ridge. The beaks are also more 
incurved than in C. rectirostris. 
Formation and locality: Lower limestone of the Trenton form- 
ation, at Minneapolis and Cannon Falls, Minnesota. Another 
specimen belonging to the Museum of the Geological Survey of 
Minnesota was found by Mr. Chas. Schuchert in the ''Lower 
Blue Ijeds" near Beloit, Wisconsin. 
Cypricardites oyiFORMis, n. sp. 
Plate vir, Figs. 3 and 4. 
Shell rather above the medium size, moderately convex, the 
outline almost regularly oval, with the posterior end a little the 
widest, and a slight straightening along the cardinal margin. 
Beaks small, situated between one-fourth and one-fifth of the 
length from the anterior extremity; erect, compressed, and not 
incurved in casts of the interior; in the shell projecting very little 
if at all above the hinge line. Urabonal ridge indistinct, with the 
point of greatest convexity a little above and in front of the mid- 
dle. In the casts there is a more or less sharply defined flattened 
strip running from the beaks downward. Hinge plate wide and 
strong, with two strong posterior lateral teeth in each valve, and 
sometimes a third small one above them, in the left valve. An- 
terior teeth consisting of one long tooth placed parallel with the 
margin of the shell in front of the beaks and five or six small 
