206 [Assembly 
Localities. Near Clarksville, Albany county, and at Schoharie, in 
the hmestone which contains the Asaphus selenurus of Eaton. It also 
occurs in the Moscow shales in Livingston county. In some varieties 
the spines are comparatively few. 
Platyceras ventricosum. 
Shell ventricose ; aperture very large and campanulate ; volutions 
three, contiguous, depressed below the upper margin of the large whorl. 
Locality. Near Clarksville. Occurs abundantly in the shaly lime- 
stone or Wenlock equivalent. 
Platyceras Gebhardii. 
Differs from the last, in having a much larger and more prominent 
spire which is longitudinally carinated near the apex and with distinct 
transverse undulated striae. Found at Schoharie by John Gebhard, Jr. 
in the same limestone which contains the preceding species. 
Cyrtoceras. 
Cyrtoceras trivolvis. 
Shell large, rounded ; with transverse waved lines of growth ; septa 
numerous. 
Locality. Schoharie ; Mr. Gebhard. 
Cyrtoceras Matheri. 
Resembles the last, but the transverse ridges are more prominent and 
distant, they meet at an angle on the middle of the back. 
Locality. Found with the preceding, by Mr. Gebhard. 
Phragmoceras spinosum. 
Shell with two rows of foliated spines. 
Locality. Sclioharie ; Mr. Gebhard. Occurs in the grit which con 
tains the Lower Ludlow species. 
Bivalves. 
Pleurorhyncus cuneus. 
Shell triangular, with radiating ribs ; umbonial slope oblique, ante- 
rior side cuneiform, rostrated ; anterior dorsal margin straight, oblique, 
thick ; sub-margin broad and separated from the disk by a deep groove. 
