194 
PALAEONTOLOGY OF NEW-YORK. 
251. 2. CYRTOCERAS ANNULATUM (n. sp.). 
Pl. XLI. Figs. 4 a, b, c, d ; and Fig. 5. 
Gradually curving, expanding towards the aperture ; surface annulated by strong ridges, 
which, with the intermediate spaces, are marked by line transverse striae ; siphuncle 
central ; septa plain. 
This species is readily recognized among all the others, at present known, in this rock, 
by its elevated annulating ridges and fine striae, in which it is very similar to some of the 
Orthocerata. The shell is pretty uniformly curved, gradually enlarging, and more abruptly 
expanding towards the aperture. It occurs in fragments, a perfect specimen not having 
been seen. The central position of the siphuncle is a departure from the usual character of 
Cyrtoceras , and on this account may be regarded as a bent Orthoceras ; but it enlarges 
more rapidly towards the aperture than ordinary species of that genus, and being constant 
in its curvature, this may be regarded as its normal form. 
Fig. 4 a. A large fragment, which is a cast, retaining the annulations. 
Fig. 4 b. A smaller fragment, retaining the shell and transverse strife. 
Fig. 4 c. Section of the last, showing the siphuncle. 
Fig. 4 d. A portion of the surface magnified. 
Fig. 5. A fragment of the same species, nearer the aperture. 
Position and locality. In the lower .shaly strata at Middleville, and in the higher crystal¬ 
line strata of the same rock at Watertown. {State Collection.) 
252. 3. CYRTOCERAS MACROSTOMUM. 
Pl. XLII. Figs. 1 a, b, c, & 3 a, b. 
Cyrtoceras marginalis. Conrad, Proc. Acad. Nat. Sciences, 1843, Vol. i, p. 334. 
Not Cyrtoceras marginale, Phillips, Pal. Fossils, 1841, pag. 115, pl. 46, fig. 219. 
Subconical, slightly incurved, rapidly enlarging from the apex; outer chamber large, 
forming about half the length of the fragment; septa closely arranged ; siphuncle dorsal; 
section not entirely circular ; surface ? 
The fragment measures four inches, the outer chamber occupying one half the length. 
There are twenty-five septa remaining in the portion preserved. The diameter of the smaller 
extremity is half an inch ; and of the larger, one inch and seven-eighths, the edge being 
broken. The septa are interrupted, and slightly bent upwards along the dorsal line, by the 
siphuncle. The elliptical form of the section is due to pressure, the natural form being 
circular. 
The larger specimen described is from Wisconsin, where it occurs associated with Trenton 
limestone fossils. Fragments of the same have been seen in New-York and in Pennsylvania. 
The fragment 3 a b is probably of the same species, since a careful examination shows that 
it is not identical with 3 c d. This specimen is marked by closely arranged lamellose strise, 
