Wincheil.] ^'^^ [J^iii- ii 



CeNTRONELLA ? FlOBA, 11. sp. 



Shell broadly ovate, rather rectilinear along the cardinal slopes, broadly 

 and slightly sinuate, or not, along the ventral comniissnre ; general form 

 of each valve a segment of a sphere. Snrface of shell very finely and 

 sharply striate both longitudinally and concentrically. 



Length, fifteen-sixteenths of an inch ; breadth, fotirteen-sixteenths ; 

 thickness of both valves seven-sixteenths. 



This species is broader and less rostrate than C. AUei, Win. (Proc. A. 

 ]Sr. S., Phil., July, 1865, p. 123,) and also less tumid around the margins, 

 besides being much more distinctly striate. 



Though I am not positive of the generic relations of this species, it ap- 

 pears to be congeneric with G. AUei. These species are both ornamented 

 with beautiful terebratuloid punctations, and both exhibit the elongated 

 ribbon-like muscular markings on the ventral valve which also charac- 

 terize the well-determined species C. Julia. In one of the specimens re- 

 ferred (provisionally) to Gf Flora, there is a low, but elongated median 

 septum in the dorsal valve, from which, near the beak, proceeds, on each 

 side, a thin horizontal, longitudinal plate, reacliing half the length of the 

 septum. In the ventral valve, the dental lamelte are feebly developed, 

 and, instead of reaching the inner surface of the valve, they curve toward 

 the median line and join each other, leaving a small space between the 

 transverse septum thus formed and the surface of the valve — being thus 

 a kind of slioe-lifter septum inserted, — or, more strictly, a trough-like plate, 

 as in Gamaro-plioria, but not, like that, supported by a median vertical • 

 plate. It is worthy of consideration whether these distinctive characters 

 are not of generic importance. The structure noticed in this specimen 

 connects Peniamerus with Terebratula, as Camarofhoria connects Penta- 

 merus with Rliynclionella. I reserve the subject for further study. 

 From bed No. 4, Sciotoville, Ohio. 



Pernopecten ? CooPERENSis, Sliuni. sp. (Mo. Geol. Rep., Pt. ii, p. 

 206, pi. C, 15.) Herzer's collection, Newark, Ohio. 



The single internal cast referred to this species is rather too narrow — 

 having about the form of P. limcBformis. It is marked by about fifteen 

 coarse radiating grooves, with some traces of smaller intermediate ones. 

 Messrs. Meek and Worthen have expressed a strong suspicion (111. 

 Geol. Rep. Ill, p. 454\ thut PerjiopecteiilimcefoQ'misand P? Shumardian- 

 us are but varieties of Amcula Gooperensis, Shum. I embrace the opportu- 

 nity to correct the impression of these authors that the surface characters of 

 P. Umceformis have not been seen in a perfect state of preservation. I have 

 impressions of exteriors of this species upon fine (almost lithographic) 

 stone, in wliich the most delicate characters are much more perfectly pre- 

 served than they generally are in fossils retaining the actual shell. Gutta 

 percha restorations from these moulds are perfectly destitute of fine ra- 

 diating striae. On the contrary, they exhibit very fine, sharp and regular 

 concentric stria3, and obsolete traces of a few straggling, irregular, discon- 

 tinuous, broad folds or undulations. This species is also distinctly nar- 

 rower than the others. With little doubt, its validity should be admitted. 



