398 
PALEONTOLOGY OF NEW-YORK. 
This species is readily distinguished by its depressed form and nearly central 
apex, consisting, when entire, of a single minute volution. The pustulose markings 
seem to be characteristic of the species. 
Fig. 3 a. The upper side of a specimen in which the apex is partially broken off. [ The 
minute volution is seen on the specimen, though not represented in the figure.] 
Fig. 3 b. Profile view of a young specimen. 
Geological position and locality. In the central part of the Lower Helderberg 
group : Schoharie county. 
Flatyceras perlatiim (n. s.). 
Plate LXI. Fig. 4 a, b. 
Shell extremely depressed-subhemispherical, with the apex subcentral 
and obtusely pointed, very gradually sloping to the margin : aperture 
nearly circular, somewhat broader posteriorly; peristome scarcely 
sinuate. 
Surface marked by fine undulating striae. 
This species is more depressed than the preceding; and from the appearance of 
the surface, which preserves but a small portion of the shell, it has never been 
marked by plications. The cast on the anterior side is contracted in a broad con¬ 
centric groove, but it presents no marks of muscular impressions. 
Fig. 4 a. View looking upon the summit of the fossil. The indentation near the summit may 
have been due to the involution of the apex of the shell, which afterwards became 
solid, as the apex of the cast is not broken. 
Fig. 4 b. An oblique postero-lateral view of the specimen. 
Geological position and locality. In the central part of the Lower Helderberg 
group : Schoharie county. 
Flatyceras calantica (n. s.). 
Plate LXII. Fig. 1, 2, 3, 4, 5. 
\ 
Shell obliquely or arcuately subconical : apex consisting of one and a 
half to two minute volutions, from which the body of the shell expands 
very abruptly, becoming extremely ventricose beiow and broadly cam¬ 
panula^ at the aperture; peristome scarcely sinuous. 
