338 THE DEVONIAN FOSSILS OF CANADA WEST. 
STROPHOMENA ING@QUISTRIATA.—(Conrad.) 
STROPHOMENA IN@QuisTRIATA —Conrad. Journal of the Academy 
of Natural Sciences of Philadelphia. Vol. 8, p 254. Pl. 14, 
fig. 2, 1839. Also compare the descriptions and figures in the 
same work of S. CREBRISTRIATA; S VARISTRIATA; S. RECTI- 
LATERIS and S. rmpressA.—Conrad. Also, S. VARISTRIATA} 
and S, VARISTRIATA, var. ARATA.—Hall. Pal. N. ¥. Vol. 3, 
p- 180,184. Also the following in the 10th Ann. Rep. Regents 
N. Y. Univ., S. in@QuiRADIATA ; 8. TEXETILIS and 8. CONCAVA. 
—Hall. 
Fig. 1138. 
Fig. 113.—Strophomena inequistriata.—Ventral view of one of the forms of this species 
6., longitudinal section. 
Description.—Semi-circular, semi-oval, or sub-triangular, width on 
hinge-line varying from one to three inches; length from two-thirds 
to seven-eighths of the width ; cardinal angles compressed, forming 
rounded or acute ears which are more or less extended. Ventral 
valve varying greatly in the amount and in the form of its convexity ; 
usually with the visceral disc depressed convex and the margin all 
round abruptly curved down for one-third or one-half the whole length 
of the shell; sometimes the shell uniformly arched from beak to 
front; the umbo often so greatly developed as to overhang the hinge- 
line and bring the area under the body of the shell; in other speci- 
mens the convexity of the umbo is continued along the middle to the 
front, producing a broad mesial carination; in many the front is 
greatly produced in a gradual slope from the anterior margin of the 
disc, and occasionally we find specimens with the front margin so much 
curved as to be to some extent inrolled under the shell; in all the 
umbo is more or less prominent, there being a somewhat flat or 
depressed sub-concave space of greater or less extent on each side 
