GASTROPODA. 257 



Remarks — This form is represented chiefly by casts, and only fragments of the 

 shell substance are preserved. The specimens are smaller than those from the Oriskany 

 of New York, but in other respects agree with them. 



Horizon — Lower beds. 



Figured specimens No. 27522, Walker Museum. 



Platyceras cf. gracile Ohern 

 Plate 68, figures 11-13 



1913. Platyceras gracile Ohern, Geol. Surv., Md. Low. Dev., p. 478, pi. 85, figs. 10-13. 



Description — Shell small, sub-conical, ascending spirally, whorls a little more than 

 one, free; shell expanding regularly from apex to aperture; aperture circular to sub- 

 circular in outline; peristome not observed. The dimensions of a large specimen are: 

 Height 30 mm., greatest diameter of aperture 16 mm. The proportionate height and 

 breadth in individuals varies to a marked degree. A fragment of shell substance ad- 

 hering to the cast shows the surface marked by irregular, transverse striations. Most 

 of the specimens have distinct spiral corrugations extending from the aperture up to 

 or almost to the apex. Apex missing in all specimens examined. 



Remarks — This shell bears a close resemblance to Platyceras gracile Ohern, from the 

 Maryland Oriskany, but it is considerably smaller, and does not have the apex so nearly 

 in the plane of the right side of the aperture. Also some of the Little Saline forms are 

 more nearly erect than those from Maryland. 



Horizon — Lower beds. 



Figured specimens No. 27523, Walker Museum. 



Platyceras magtiificum Hall 



Plate 68, figures 14-17 



1859. Platyceras magnificum Hall, Nat. Hist. N. Y. Pal., vol. 3, p. 476, pi. 119, figs. 



1-6, 1861. 

 1913. Platyceras magnificum Ohern, Geol. Surv., Md. Low. Dev., p. 472, pi. 82, figs. 

 1-6. 



Description — "Shell obliquely subovate. Spire depressed below the plane of the 

 outer volution; volutions two or three, very rapidly expanding and becoming extremely 

 ventricose below, usually free or with the first one contiguous, aperture expanded sub- 

 circular, campanulate, and often with the margin reflexed, particularly on the left 

 side. Surface marked by distinct, transverse, lamellose, undulating striae." — Hall, 1859. 



Remarks— The specimens in the collection are all casts of the interior, but patches 

 of shell are attached and display sinuous lines of growth. The species differs from 

 Diaphorostoma ventricosum Hall, in the more rapid expansion of the whorls, in the free- 

 dom of the volutions, and in the wider and more expanded aperture. Character of 

 peristome obscure in all specimens observed. 



Horizon — Lower beds. 



Figured specimens No. 27529, Walker Museum. 



Platyceras cf. multisinuatum Hall 

 Plate 69, figure 1 



1859. Platyceras multisinuatum Hall, Nat. Hist. N. Y. Pal., vol. 3, p. 319, pi. 58, figs. 



8a, b, c and 9a, b, 1861. 

 1913. Platyceras multisinuatum Ohern, Geol. Surv., Md. Low. Dev., p. 477, pi. 85. 



figs. 4-6. 

 Description — "Shell subdiscoid in the young state; apex nearly on a plane with 

 the outer volution; volutions about three, the first one minute; outer one becoming 



