AMERICAN PALEOZOIC CEPHALOPODS 
257 
and for a width of 25 mm., thus locating the hyponomic sinus 
at earlier stages of growth. A partially exfoliated conch, num- 
bered 3195 at the Public Museum of Milwaukee, Wisconsin, dis- 
plays vertical bands and striae in addition to the transverse 
bands. 
Location and horizon, — In the original description of the 
species, Racine is mentioned first as a source of material, but 
the type is from Waukesha, Wisconsin. It is numbered 2112 in 
the American Museum of Natural History. 
Remarks, — In the 20th Report of the New York State Cabinet 
of Natural History, cited above, the generic reference of this 
species is changed from Cyrtoceras to Oncoceras, but the type of 
the latter is a Trenton form, compressed laterally, not depressed 
dorso-ventrally as in the Racine species here described. More- 
over, the segments of its siphuncle are rather narrowly fusi- 
form, instead of cylindrical or barrel-shaped in outline. 
Numerous specimens of Amphicyrtoceras orcas are in the 
Greene Museum at Milwaukee-Downer College, in Milwaukee, 
Wisconsin. 
47. AMPHICYRTOCERAS LATERALE (HALL) 
PLATE XXX, FIGS. 1 A-D, 2 A, B 
Cyrtoceras laterale Hall; 20th Rep. New York State Cab. Nat. Hist., 
1868, p. 357, pi. 18, figs. 4, 5, 6 
Type , — Cyrtoceracone comparatively little curved. The length- 
wise dorsal outline is nearly straight. The corresponding ven- 
tral outline is curved lengthwise with a radius of 150 mm. The 
specimen consists of a phragmacone, with only the basal part of 
the living chamber still attached. The lateral diameter of the 
phragmacone increases rapidly from 17 mm. at the base to 
37 mm. at the top of the eighth camera from the smaller end. 
From this point upward, for a distance of 4 camerae, the lateral 
diameter remains about the same. The contraction near the base 
of the living chamber is slight. At the smaller end of the phrag- 
macone the transverse section is nearly circular, the dorso-ven- 
tral diameter being 17 mm. Farther up, the conch rapidly be- 
comes depressed dorso-ventrally. At the top of the eighth 
camera, the cross-section is transversely elliptical, the dorso-ven- 
tral diameter being 28 mm. The curvature of the conch in a lat- 
