474 Systematic Paleoktology 



face, indicating the exii^tence of a marginal notcli at some period of 

 growth.'' Hall, 1859. 



Occurrence. — Heldekberg Foriiation, Xew Scotland Member. 

 Corriganville. Oriskany Formation, Eidgely Member. Cumberland, 

 east side Nicholas Mountain. 



Collections. — Maryland Greological Survey, U. S. Xational Museum. 



[Ohern.] 



PlATYCERAS ? CALLOSUM Hall 



Plate LXXXIV, Figs. 3, 4 



Platyceras ? {Platyostoma ?) callosum Hall, 1859, Nat. Hist. N. Y., Pal., vol. 

 iii, p. 478, pi. cxx, figs. 8a, 6, 1861. 



DescripUon. — " Shell obliquely ovoid, ventricose. Spire consisting of 

 about three volutions; the apex minute, and the first two volutions nearly 

 in the same plane ; the last volution expanding greatly below. Aperture 

 suborbicular : peristome continuous, thickened and coalescing with the 

 body volution at its lower side ; the umbilical cavity closed by a callosity ; 

 the shell, approaching the aperture, becoming lamellose ; the lamella; ele- 

 vated and imbricating. Surface marked by undulating transverse stria; and 

 obscure revolving striag, with obsolete parallel undulations. The lines of 

 growth are strongly arched forward on the middle of the back of the 

 shell." Hall, 1859. 



Occurrence. — Oriskany Formation, Eidgely ^Member. Cumberland 

 (fide Hall). 



Collection. — x\merican Museum of Natural History. 



[Ohern.] 



Platyceras sinuatum Hall ? 

 Plate LXXXIV, Figs. 5, G 



Platyceras sinuatum Hall, 1859, Nat. Hist. N. Y., Pal., vol. iii, p. 314, pi. Iv, 

 figs. 5,7; pi. Ivii, fig. 2, 1861. 



Description. — " Shell depressed, somewhat obliquely ovoid : volutions 

 al)()ut three, contiguous, the last one becoming very ventricose, a little 

 flattened on the upper side, and expanded laterally to the axis of the spire : 



