PALEONTOLOGIC CONTRIBUTIONS 75 



It has also finer longitudinal striae which do not extend to the 

 anterior portion of the valve and the extremity of its posterior 

 wing is not produced but truncated. 



Ctenodonta ? salinensis nov. 

 Plate 25, figures 8 and 9 



Description. Shell small, inequilateral, moderately elongate- 

 ovate, the length surpassing the height by one-half, quite flat. Beak 

 widely obtuse, projecting a little beyond hinge line, far forward 

 (about one-third of length from anterior extremity). Dorsal line 

 convex, sloping downward from beak to the narrowly rounded 

 posterior extremity. - . Anterior end considerably wider than the 

 posterior, and anterior margin more fully rounded. Ventral 

 margin but gently convex. An obscure umbonal ridge with its 

 shoulder close to the dorsal margin, is traceable nearly to the 

 posterior margin. Above it a narrow impressed strip is seen along 

 the dorsal margin. The surface is flat, sloping from the umbonal 

 ridge fairly evenly to the ventral and anterior margins. Fine 

 growth-lines with a few coarser ones are observable on the whole 

 surface. The hinge and the muscle impressions have not been 

 observed. 



Measurements. Length of average shell 12.5mm, height 8 mm, 

 thickness about 1 mm. 



Horizon and locality. Salina beds at Bull's quarry, town of 

 Lenox, Madison county. 



Remarks. The sole interest in this insignificant little pelecypod 

 consists in its occurrence in the Salina beds close to the gypsum 

 beds. The Salina beds, where the salt-pan conditions that began 

 in the Pittsford shale and waterlime reached their climax and led 

 to the deposition of the well-known salt and gypsum deposits of 

 the State of New York, appear to the collector as absolutely barren 

 of fossils. It is true, Prof. James Hall 1 described in 1851 eight 

 small marine fossils from the " Onondaga Salt Group " of Wayne 

 county. Mr C. A. Hartnagel, however, states that these were, 

 obtained from a Guelph boulder in the Salina belt. As a matter of 

 fact they are Guelph species. Ctenodonta ? salinensis, 

 however, is a true Salina species. It must have locally been quite 

 common, for we have before us, on a slab measuring 3 by 4 ifiches, 

 some eighteen specimens. Mr Hartnagel states that he has also 



1 Pal. of New York, 2:340. 151. 



