OF DENISOX UNIVEKSITV. ^5 



than the length of the valve, nevertheless we dislike to attempt to dis- 

 tinguish it from a species confessedly founded on a single imperfect 

 ventral valve. Our specimen, however, has no spines and a com- 

 pound dischotomy of the stria?. Sandy layers of congl. I, '• Dug- 

 way," near Granville. 



Clionctes Jo^aui, Nor. ami Trait. 

 Plate VII, Fig. 22; Plate III, Fig. 12?) 



In Fig. 22, Plate VII, the radiating costae are not distinct enough, 

 while the specimen figured on Plate III may prove to be C. fnulticos- 

 ta, Win. C. logani seems to be distributed throughout the series up to 

 congl. II, at least. 



The confusion introduced into this genus by identifying this spe- 

 cies with C. illinoisensis, has been corrected by Prof Winchell. 



Chonetps illinoisensis, Worthen. 

 (Plate III, Fig. 21.) 



Rather large for the genus, transversely semioval ; moderately 

 convex ventrally ; length between two-thirds and three-fourths the 

 width ; hinge lin? nearly equal to greatest width, with five or six small 

 oblique spines on either side of the inconspicuous beak ; ears some- 

 what flattened ; nearly rectangular; front margin a broad curve ; sur- 

 face of ventral valve rather evenly convex, highest near the middle, 

 casts showing a strong mesial septum; c'orsal valve gently concave, 

 with distinct cardinal 'eet . Surface ornamented with about 100 bi- 

 furcating, thread-like stria:. Length 7 mm ; width 1 1 mm. Our speci- 

 mens rarely attain the size of the western ones, though often much 

 larger than the above measurements. 



Found in the sandy rock above congl. I; also forty feet or more 

 below this horizon at Moot's run. The sj)ines of this spf. i... .r.. .^nrh 

 more slender and curved than in S. scitula. 



