300 PILJEONTOLOGT OF NEW-VOKK. 



Position and locality. This species occurs in the soft shaly portions of the group, at 

 Pulaski, Loraine, and other places. I have obtained casts of the same from the ferruginous 

 sandstones in the higher part of the group. It occurs likewise at Cincinnati, and several 

 other western localities. 



359. 3. ORTHONOTA CONTRACTA (n. *j9.) 



Pl. LXXXII. Figs. 8 a, b. 



Subcylindrical, slightly arcuated ; beaks distinct, acute, with a prominent oblique carina 

 extending towards the posterior basal margin, which is arcuated, and the shell much 

 contracted below and posterior to the beaks; dorsal mtUgin broad, rounded, the valves 

 strongly marked by oblique folds. 



The extremities of the shell are wanting in the two specimens which I have. It differs 

 from the last, in having more acute and distinct beaks, with the cardinal margin broader. 

 The base is arcuate, and distinctly contracted, or sinuate, a little behind the beaks. It ia 

 possible that this may prove identical with the last, since I have been unable to examine 

 perfect specimens. 



Fig. 8 a. The left valve, showing the distinct carina and concentric striiB of the surface. 

 Fig. 8 b. Dorsal view of the same, showing the oblique wrinkles on the posterior cardinal margins of 

 the shell 



Position and locality. This species occurs in the soft marls at Cincinnati, Ohio. I have 

 not seen it from other localities. 



360. 1. CLEIDOPHORUS PLANULATUS.» 



Pl. LXXXII. Figs. 9 a, b, e, d, e. 



JViieulUa planulata. Cokbad, Ann. Report, 1841 , p. 48. 



— tcitula. Conrad in MS. Emmons, Gepl. Report, pag. 399, fig. 2. 



Subelliptical, with the anterior extremity narrowed, regularly rounded ; posterior side 

 broader ; beak scarcely elevated ; a distinct impressed line extending from before the beak, 



* AU the specimens of this species which I have examined, show no crenulations upon the cardinal margin, which 

 is nearly direct and stubalate posteriorly. There is no visible muscular impression as in Modioloptia ; and the strong 

 linear depressed line in the casts indicates the existence of a rib, or clavicle, as in Solecurtiu. This character, which 

 is very conspicuous in several species in the higher strata, pertains to shells having a similarity of form, which i» 

 nearly like the one figured. For shells of this character, I propose the following generic name : 



Gents CLEIDOPHORUS. 



[Greek, xklt&ns, clavicle, and ^cpo, to bear ; in allusion to the clavicle in each valve, anterior to the beak.] 



The shells of this genus may be characterized as, equivalved, inequilateral; hinge without teeth or crenulations; 

 ■urface (particularly in casts) marked by an oblique linear depression, extending from the anterior cardinal margin 

 towards the base, indicating the place of the clavicle ; surface concentrically striated. 



