34 A Contribution to the Lower Devonian Faunas of Maryland 



Platyceras sinuatum Hall ? 

 Plate LXXXIY, Figs. 5, 6 



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 obliqiiety ovoid : volutions 

 about three, contiguous, the last one becoming very ventricose, a little 

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

 aperture broad, campanulate ; margin deeply sinuate. Surface marked by 

 fine concentric or transverse lamellose strige, and stronger wrinkles or 

 folds. The stria? are abruptly bent backwards on the upper dorsal side, 

 and a deep sinus marks the labrum : the lower side of the a])erture is like- 

 wise deeply sinuate." Hall, 1859. 



Occurrence. — Oriskany" Formation, Eidgely' Member. East side 

 Nicholas Mountain. 



Collection. — Maryland Geological Survey. 



Platyceras trilobatu:m Hall ? 

 Plate LXXXIV, Figs. 7, 8 



Platyceras triloMtum Hall, 1859, Nat. Hist. N. Y., Pal., vol. iii, p. 316, pi. Ivii, 

 figs. 5a, b, c, 1861. 



Description. — " Body of the shell obliquely or arcuately ovoid, trilobate : 

 volutions three or four, the last one (or more) becoming free, gradually 

 expanding to the aperture ; the apex closely invohed and rising above the 

 plane of the outer volution, or sometimes on the same plane, concave 

 towards the suture : aperture subangularly ovate, sinuate on the right and 

 left sides, and the shell extended in front. Surface marked by two strong 

 spiral depressions corresponding to the sinuosities of the aperture, and 

 crossed by lamellose striae which are strongly undulated on the sinuosities 

 of the last volution, and are marked by other undulations on the earlier 

 volutions, indicating former sinuosities in the margin of the aperture." 

 Hall, 1859. 



A specimen in tbe U. S. Xational IMuseum is much smaller than those 

 figured by Hall, but in other respects closely resembling this species. The 

 three sinuses are shown better by the undulating strine on the surface than 



