258 
AUG. F. FOERSTE 
eral direction is slightly greater on the ventral than on the 
dorsal side. 
The sutures of the septa curve slightly downward along the 
median parts of the ventral side, especially near mid-length of 
the phragmacone. The location of the siphuncle at the smaller 
end of the specimen is indicated by a small circle, 1.5 mm. in 
diameter, with its center 3 mm. from the ventral wall of the 
conch. Very faint, low. broad, almost obsolete vertical ribs, 
about 7 in a width of 20 mm., are seen on casts of the interior 
of the conch. 
Locality and horizon . — From Racine, Wisconsin, in the Racine 
member of the Niagaran. Specimen numbered 2119 in the 
American Museum of Natural History. 
Mihvaukee Museum specimen. — Another specimen, numbered 
634 in the Public Museum of Milwaukee, Wisconsin, consists of 
the living chamber and 6 upper camerae. The maximum width, 
49 mm., occurs at the first camera beneath the living chamber. 
The contraction of the upper part of the living chamber begins 
8 mm. above the base of the latter. The height of this living 
chamber is 44 mm. It contracts from a width of 49 mm. at its 
base to an estimated width of 39 mm. at its top. The correspond- 
ing dorso-ventral contraction is estimated from 44 mm. at its 
base to 35 mm. at its top. The phragmacone is distinctly, though 
gently, concave along its dorsal lengthwise outline. The sutures 
of the upper septa slant slightly downward toward the ventral 
side, and curve more strongly downward along the median part 
of the latter, for a vertical distance of 3 or 4 mm. and for a 
width of 25 mm. Farther down, the curvature of the sutures 
becomes less conspicuous. The siphuncle is situated about 
3 mm. from the ventral wall of the conch. Its segments are 
somewhere between short cylindrical and barrel-shaped in ver- 
tical outline. At the uppermost camera its diameter is almost 
6 mm., diminishing at its passage through the septum to 3 mm. 
The septal necks are short, about half a millimeter in length. 
The cast of the interior of the phragmacone is marked by nearly 
obsolete vertical ribs, extending upward along the lower half 
of the living chamber, but becoming very indistinct there. 
Remarks. — Amphicyrtoceras laterale evidently is closely re- 
lated to- Amphicyrtoceras orcas, and there is a possibility of their 
being specifically identical. At present, the vertical ribbing of 
