Weller — Kinderhook Faunal Studies. 23 



of the shell, its anterior margin slightly convex or nearly 

 straight, meeting the lateral margin of the shell below nearly 

 at right angles ; the posterior margin of the posterior ear con- 

 cave, forming with the lateral margin of the shell below, a 

 rather wide, rounded or subangular sinus. Beak erect, 

 extending slightly beyond the hinge-line. Surface orna- 

 mented by radiating subangular costae, either nearly equal in 

 size or with alternate smaller ones intercalated towards the 

 margin ; the spaces between the costae wider than the costae 

 themselves. Crossing the radiating costae there are numer- 

 ous, much finer and more crowded concentric striae. The 

 ornamentation upon the ears is much less conspicuous than 

 upon the body of the shell. 



The right valve is more compressed than the left, with pro- 

 portionally longer hinge-line and larger ears, and without 

 ornamentation. 



Remarks. The specimens which are referred to this spe- 

 cies are all more or less imperfect, but they agree closely 

 with the description and illustrations of C . winchelli from the 

 Waverly sandstones of Ohio. They have also been compared 

 directly with Ohio specimens. The one character in which 

 the Northview specimens differ from those from Ohio, is in 

 the almost complete absence of radiating costae upon the ears 

 of the left valve. In the Ohio shells the ornamentation upon 

 the ears is almost as conspicuous as upon the remainder of 

 the shell. It is possible, therefore, that with more perfect 

 material the Northview specimens might be shown to belong 

 to a distinct species, though one closely allied to C . winchelli. 

 The crenate hinge-line of this genus is well shown upon 

 several of the specimens. 



Ckenipecten laevis n. sp. 



PL IV. f. 14. 



Shell flabelliform, slightly oblique, attaining a height of 

 29 mm. and a length of 31 mm. in the type specimen. Basal 

 and lateral margins rounded, straightened above and if con- 

 tinued to the beak they meet at an angle of about 105°. 

 Hinge-line a little more than one-half the greatest length 

 of the shell. 



