A COXTEIBUTION TO THE LoWER DEVONIAN FauNAS OF MARYLAND 33 



Description. — '' Shell spiral, obliquely or arcuately siibconical, spirally 

 ascending; the apex consisting of one or two free, but closely approxi- 

 mating volutions; the body volution diverging, and spreading somewhat 

 rapidly towards the aperture : aperture broad, the peristome often sinuous 

 and sometimes abruptly expanded: volutions round or subangular, and 

 rarely distinctly angular, with the aperture subquadrate. Surface trans- 

 versely striate; the striae sometimes bent abruptly backwards on the sur- 

 face, indicating the existence of a marginal notch at some period of 

 growth/' Hall, 1859. 



Occurrence. — Helderbeeg Foematign^ jSTew Scotland Member. 

 Corriganville. Oriskany Formation, Eidgely Member. Cumberland, 

 east side Nicholas Mountain. 



Collections. — Maryland Geological Survey, U. S. National Museum. 



Platyceras ? callosum Hall 

 Plate LXXXIV, Figs. 3, 4 



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

 ill, p. 478, pi. cxx, figs. 8a, &, 1861. 



Description. — " 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 lamellEe 

 elevated and imbricating. Surface marked by undulating transverse striae 

 and obscure revolving strise, 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. — American ^Museum of Natural History. 



