<» 



30 SIXTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



Anotlier specimen of similar character, but with the apex a little more 

 depressed, has a length of half an inch, with a transverse diameter of about 

 one inch. This specimen is essentially a cast in sandstone, and its surface 

 markings are not clearly preserved ; but it shows no important difi'erence 

 from the preceding one, and for the present I unite the two under the same 

 designation. 



Geological formation and locality. In the shales of the Chemung group : 

 near Elmira, Chemung county ; and in sandstone of the same group near 

 Wellsborough, Pennsylvania. 



" DISCINA NEWBERKYI ( n. s.)." 



Shell subcircnlar or broadly ovate, sometimes oblate : apex 

 situated near the posterior margin or less than one-fourth the 

 ' length of the shell therefrom, prominent, being from less than 

 one-eighth to one-quarter of an inch above the plane of the 

 margins. Ventral valve slightly concave ; apex excentric ; fo- 

 ramen large, oval, with the margins deeply depressed. Shell 

 comparatively thick and strong. 



Surface marked by fine concentric lines, which are very faint in 

 young shells, but become stronger and rise into distinct sharp- 

 ly elevated strige in older specimens. 



Where partially exfoliated, the shell shows intermediate fine ra- 

 diating striae; and in older specimens, the interior of the shell, 

 and likewise the cast, is marked by strong radiating vascular 

 impressions. The structure of the shell is strongly lamellose. 

 The casts of the dorsal valve show a narrow longitudinal mu- 

 scular impression on the anterior side of the beaks. The length 

 varies from one-eighth to one inch. 



For these specimens, I am indebted to Dr. J. S. Newberry. 



Geological formation aycd locality. Abundant in a ferruginous band 

 about 110 feet below the Conglomerate at Cuyahoga falls, and in the green 

 shale and shaly sandstone at Akron, Ohio. 



GENUS CRANIA ( Retzius). 



" CRANIA AURORA ( n.s.)." 



A cast of Trochoceras, from the Schoharie grit, preserves the 

 impressions of two individuals of a species of Crania, which were 

 apparently adhering to the interior of the shell of the outer 

 chamber of this cephalopod. 



Ventral valve subquadrate, approaching a circular form ; lateral 

 margins slightly curved, and the two extremities abruptly 



