100 The American Geologist. August, 1892 
unequal teeth running downward from the horizontal tooth. An- 
terior muscular scar distinct, elongate, vertically disposed, situ- 
ated immediately beneath the cardinal teeth. Posterior scar illy 
defined. Shell substance thin except in the anterior and dorsal 
regions. 
The small vertically arranged anterior teeth, and the erect and 
strongly compressed beaks of casts of the interior, are the two 
principal peculiarities of the species. These and other equally 
obvious characters distinguish it from its perhaps nearest con- 
gener, C. ohtusifrons Ulrich. C. glaheUus Ulrich, from the 
shales, is wider in front and diflferently outlined posteriorly. 
Formation andlocaJity: Two opposite valves were collected by 
Mr. Chas. Schuchert, at Janesville, Wisconsin, in the "Lower 
Blue limestone." These are now in the museum of the Geologi- 
cal and Natural History Survey of Minnesota. 
Mus. Reg. No. 8324. 
Cypricardites(?) modestus, n. sp. 
Plate VII, Figs. 5-7. 
Shell small, ol)lique, moderately ventricose, obliquely ovate in 
outline, known from casts of the interior only. In these the an- 
terior end is very small, sharply rounded, abruptly depressed be- 
neath the beaks, and almost entirely occupied by a subcircular 
muscular scar. Beaks small, only slightly incurved, appearing 
prominent from the front but not from the back. Umbonal ridge 
scarcely distinguishable, the cardinal slope faintly concave be- 
tween it and another low ridge-like swelling that forms the 
back of the cast. Along the hinge line there is a narrow im- 
pressed area. Shell thin; hinge-plate narrow, dentition undeter- 
mined. 
The generic position of this shell is doubtful, I having thus 
far failed in my efforts to make out the dentition of the hinge. 
From the narrowness of the hinge-plate I am satisfied that there 
cannot be more than a single posterior lateral tooth, if any. It 
is possible that the species is a Matlirria with relations to the 31. 
rugosa^ recently described by me from a lower horizon in the 
shales, in which the anterior muscular impression is as in the 
present species deeper than usual in that genus. It is clearly, I 
think, not a Modiolopsis, and until more is learned of its hinge it 
seems best to arrange the species as above. 
