152 PALEONTOLOGY OF OHIO. 



ventral end it is prolonged into a tube-like projection, extending to a 

 distance beyond the limits of the shell below, about equal to one-fourth 

 of the lateral diameter of the outer chamber at its widest part. The 

 septa, only two of which are preserved in the specimen figured, are pro- 

 portionally distant, slightly concave, and but little curving upwards at 

 the dorsal and ventral portions. Siphuncle minute, situated close to the 

 inner margin. Exterior surface unknown. 



The species differs from any other described in its small size, in the 

 general form and rapid curvature, combined with the protruding tube- 

 like process at the ventral extremity of the aperture. 



Formation and locality : In the limestones of the upper part of the Niagara group, at 

 Cedarville, Greene county, Ohio. Ohio State collection. Collected by Prof. E. Orton. 



Phragmoceras ellipticum (n. sp.). 



Plate S, fig. 11. 



Shell of large size, slightly curved, transverse section narrowly ellip- 

 tical, a very little wider on the outer than on the inner side of the cen- 

 ter. Outer chamber wider than high ; very depressed convex on the 

 sides, and sharply rounded on the dorsal and ventral edges ; the ventral 

 side extended at the aperture, forming a tube-like projection ; the re- 

 mainder of the aperture not known. First chamber below the chamber 

 of habitation very snallow ; septa deeply concave; siphuncle large, 

 situated close to the inner side of the shell. 



The specimen used in description consists of the cast of only the outer 

 chamber and a fragment of the filling of the next chamber below, and 

 is, moreover, imperfect at the upper extremity ; but the form of the 

 transverse section is so very distinct from any other species yet de- 

 scribed that it is readily characterized, and as readily distinguished 

 from any other species. The shell has been of very large size, the frag- 

 ment used measuring nearly four inches in width, with a height of three 

 and a quarter inches, the thickness from side to side being only a little 

 more than one and a half inches. The peculiar narrow form of the trans- 

 verse section is a good distinguishing feature. 



Formation and locnlity : In the limestones of the Niagara group, in Highland coun- 

 ty, Ohio, associated with Trimerdla OJdoensis. Ohio State collection. Collected by 

 Prof. Edward Orton. 



