474 
PALAEONTOLOGY OF NEW-YORK. 
Platyceras subnodosum (n. s.). 
Plate CXY. Fig. 7. 
Shell spiral, consisting of about a single volution which is nearly in the 
same plane : volution rapidly expanding from the apex, and somewhat 
quadrangular, being flattened on the sides and back, with an obscure 
row of subdued nodes along each angle. 
The specimen is a cast, preserving in one part an impression of the shell, which 
is transversely striate, with the stria; undulating or tortuous at the nodes. 
This species is quite distinct from the preceding, in form of volution, arrangement 
of nodes, etc. 
Fig. 7. View of the upper side of the spire. 
Geological position and locality. In the Qriskany sandstone : Schoharie county. 
Platyceras gefohardi. 
Plate CXVII. Fig. 1 - 10. 
Platyceras gebhardi : Conrad. See page 312 of this volume. 
The specimens figured on Plate cxvii were obtained several years after the figures 
on Plate lvi had been engraved, and serve to establish more fully the character of 
the species, as well as to prove its existence in the Oriskany sandstone. 
The specimens of this series are very interesting; showing some forms where the 
peristome is free, and others where it is spread over the convexity and adhering to 
the preceding volution, even so far as to be recurved; forming in fact a columellar 
lip, and leaving a distinct umbilicus as shown in figures 1, 2, 4 & 5. In a single 
specimen of large size, not figured, the peristome adheres to the volution, and the 
convexity of the latter is shown projecting within the.otherwise symmetrical aper¬ 
ture. In another specimen of medium size, the peristome is so closely incorporated 
with the adjacent volution as to leave only a callosity on the lower half; while 
below the volution the peristome is a little recurved, and the shell deeply umbili- 
cate. In this specimen, the continuity of the peristome would hardly be suspected 
or observed. 
Fig. 1 a, b. A young shell, in which the peristome is closely adhering to the body whorl. 
Fig. 2. A similar specimen with the preceding. 
Fig. 3 a, b. A larger individual of the same character. 
