jL Winchell on supposed New Cephalopods. [358] 9 
This impression agrees in form, dimensions and distance of 
rings with 0 . dactyliophorum de Kon. (An. Foss., pi. xvii, 2). 
But this species is described as haying circular strias without any 
longitudinal ones. It differs from 0. tenuilineatum Sandberger 
(Yerstein., Taf. xix, 7) by the greater approximation of the rings, 
and much more closely striated surface. This species, however, 
from the “ Orthocerasschiefer ” of Wissenbach, seems at least to 
be a close analogue. Our fossil is perhaps identical with 0. an- 
nulatum of Hisinger, but I have no access to a description of 
that species. 
Nautilus (Trematodiscus) planidorsalis, n. sp. 
(non N< planidorsatus Portlock.) 
Shell small, closely coiled, but the whorls not impressed; sec¬ 
tion angular, transverse diameter greater than the dorso-ventral. 
Dorsum perfectly flat and quite broad, marked by a strong longi¬ 
tudinal groove near each lateral boundary. From the dorsal area 
the surface bends Abruptly down the dorso-lateral area, making 
with the dorsum a slightly rounded angle of 125°. The dorso¬ 
lateral area is half the width of the dorsum and is slightly con¬ 
cave. From the dorso-lateral area the surface bends regularly 
toward the umbilicus, but with an increasing radius of curva¬ 
ture. The umbilico-lateral area is marked by strongly raised, 
sharp, longitudinal striae, which, under a lens, are seen to be 
decussated by fine, raised, transverse striae, less rigidly direct 
than the former ones, more strongly marked where crossing the 
longitudinal striae, and giving them a kind of moniliform ap¬ 
pearance. Indications of longitudinal striae exist over the whole 
surface, but the state of the specimen is unfavorable for their 
exhibition. The septa present a shallow, posterior sinuation in 
the middle of the dorsum, a similar anterior sinus on the dorso¬ 
lateral angle, and a slight posterior sinus on the lower portion 
of the dorso-lateral area. 
Diameter of whorl *76 (100); greatest transverse diameter of 
section ’43 (57); dorso-ventral diameter of section *25 (33); 
greatest width of dorsum *22 (29); greatest width of dorso¬ 
lateral area T9 (25); distance of longitudinal stride *012 (1*6), 
giving 8 to one-tenth of an inch; distance of transverse striae 
*008 (1*0), giving 13 to one-tenth of an inch; greatest distance 
between the furrows on the dorsum T8 (23); greatest distance 
between septa, measured on the dorsum T4 (18). 
Locality. Marshall. 
The best specimen of this species in my possession is a frag¬ 
ment showing about half of one whorl from the septate portion 
of the shell. The species belongs to the group of angulated, 
widely umbilicated Nautili for which Messrs. Meek and Worthen 
have proposed the distinct subgeneric designation Trematodiscus 
2 
