262 
AUG. F. FOERSTE 
verse curvature of the conch, but so slight is this outward curva- 
ture that it is likely to escape attention. An accentuation of this 
outward curvature would lead to forms such as those included 
under Streptoceras. ‘Within 5 or 10 mm. from the aperture the 
dorsal and ventral walls of the cast of the interior of the living 
chamber curve slightly outward. The surface of the shell is 
striated faintly in a transverse direction, and weathered parts 
of the surface show very faint vertical striae. 
Location and horizon. — Schoonmaker’s quarry, at Wauwatosa, 
Wisconsin, in the Racine member of the Niagaran. No. 2312, in 
the Museum of Comparative Zoology, at Harvard University. 
Flattened Wauwatosa phragmacone. — The specimen consists 
of 15 camerae, no part of the living chamber being retained. It 
is of interest chiefly because it gives some idea of the rate of in- 
crease in the size of the conch, notwithstanding the fact that it is 
strongly compressed dorso-ventrally, evidently during fossiliza- 
tion. This flattening probably is due to vertical compression of 
the enclosing strata. There is no evidence that the width of the 
specimen was increased by this flattening. The height of the 
camerae agrees very well with that of the camerae in the type 
specimen from Greenfield, Wisconsin. 
Specimen No. 2301, in the Museum of Comparative Zoology, 
at Harvard University. From Wauwatosa, Wisconsin. 
50. DIESTOCERAS GEN. NOV. 
Genotype: Gomphoceras indianense Miller and Faber 
Conch relatively erect, practically without any lengthwise cur- 
vature, though possibly gently curved in its initial stages of 
growth. There is only a slight difference in the lengthwise cur- 
vature of the dorsal and ventral sides of the upper part of the 
conch. The siphuncle is located close to the ventral wall, and 
the segments are so low and broad as to appear nummuloidal. 
The walls of the living chamber converge toward the aperture, 
but the latter is much less contracted than in Gomphoceras. On 
the contrary, the aperture remains relatively wide open, with 
only a moderate angularity on the ventral side, along the hypo- 
nomic sinus. The hyponomic sinus is relatively shallow and does 
not form a lobe distinct from the remainder of the aperture. 
Gomphoceras indianense Miller and Faber is selected as the 
genotype, because this species is by far the most abundant, at 
