OF DENISON UNIVERSITY. 
103 
the lateral lobes in E. Thresheri, shows 4 tubercles, and the anterior 
segments probably presented more. 
Encrmiirus punctatus^ Hall^ from the Clinton Group of New York, 
if it be identical with Encrinurus omatiis, will of course be distin- 
guished by the same characters as those mentioned under that species; 
the number of tubercles or nodes in the New York and Ohio Clinton 
specimens and the size of the pygidia, however, agree better than 
when the pygidia of the New York and Ohio Guelph specimens are 
compared. At any rate, the Clinton forms are distinct from the typi- 
cal specimens of E. punctatus from Europe, and from the species de- 
scribed as E. ornatus^ from the Guelph strata of Ohio. 
Named after Mr. B. B. Thresher, of Dayton, in whose cabinet the 
type specimen is found. 
Locality and position. Clinton Group. 
GASTEROPODA. 
Genus BUCANIA, Hall. 
Bucania trilobata. Hall. 
{Elate VIII, Eig. 33, a, b.) 
Shell convolute, volutions in the same plane, contiguous ; later- 
ally compressed. Body of the shell strongly lobed, the dorsum being 
laterally compressed and thus separated by a sort of groove from the 
lateral portions of the volution, giving rise to one dorsal and two lat- 
eral ridges or lobes. The form of the aperture is not seen in our Ohio 
specimens, but would naturally conform to the trilobate structure of 
the last volution. 
Authors are inclined at present to abandon the genus Bucania, 
and to place the forms referred to it among the Bellerophons. We 
have seen fit to retain this name in this case purely as a matter of con- 
venience. There is already a species called Bellerophon tiHlobatus, de- 
scribed by Sowerby, in his “Silurian System”, a European form. 
From this our form may be readily distinguished by the lateral com- 
pression of its last volution. The European form on the other hand 
has this volution decidedly flattened transversely, being elliptical in 
section ; the middle lobe is comparatively much broader and not so 
much elevated above the lateral lobes. Our specimen differs from the 
New York types chiefly in size, being comparatively exceedingly small. 
