No. 109.] 147 



Stropkomena carinata, and some of the specimens before me are from the 

 same locality and position as those investigated by him. I am inclined to 

 think there must have been a typographical error in printing the name of 

 this species in the Journal of the Academy, both because there is no 

 carina about the shell, and because Mr. Conrad had previously (1839) 

 applied that name to a shell supposed to belong to the same genus. 



I am much inclined to think our shell is identical with C. maclurea of 

 Norwood and Pratten. Their figures and description agree very nearly 

 with specimens of this species of the same size as those tlicy figure, excepting 

 that their shell appears to have had one spine more on each side of the beaks. 



Geological position and locality. Hamilton group : Seneca lake shore, 

 Moscow, etc. 



Ch5.\ETES COaONATA. 



Chonetes scitula ( n. s.). 

 Shell small, semicircular ; hinge not quite equalling the greatest 

 breadth, obtusely angular at the extremities : dorsal valve 

 concave ; area narrow, inclined forwards from the hinge-line, 

 having a small projecting dental process in the centre : ventral 

 valve convex in the middle, depressed at the extremities; beak 

 small, slightly convex ; area narrow and arcuate, having five 

 tubular spines along the margin on each side of the beak, of 

 which the two or three inner ones are very small or mere gra- 

 nules, while the outer two are larger and a little removed from 

 the extremities of the hinge ; foramen small, broad triangular, 

 closed above by a convex deltidium, and below by the strongly 

 projecting dental process of the other valve. Surface ornamented 

 by distinct abruptly rounded strig?, of which twelve to eighteen 

 may be counted near the beaks ; but from the bifurcation and 

 intercalation of others between these, the number is increased 

 on the margin to about fifty or sixty. Traces of concentric striae 

 are obscurely visible on all the specimens before me, and in 

 some instances they may be quite conspicuous. 



