THE DEVONIAN FOSSILS OF CANADA WEST. 349 
STROPHOMENA MAGNIVENTRA.—(Hall). 
Of this species, I have only seen some fragments, shewing casts of 
the area of the ventral valve and muscular impressions. It appears 
to be closely allied to S. magnifica, and occurs in the rock in the 
same localities. 
The specimens of these two species in our possession agree exactly 
with Professor Hall’s figures. I am endeavouring to procure mater- 
ials to illustrate them properly. 
Genus Cuonetes.—(Fischer). 
This genus differs from Strophomena in some internal characters, 
which cannot be very well described without the aid of good illustra- 
tions. The shells are in general much smaller than those of Stropho- 
mena; they are more evenly striated, and the cardinal edge of the 
ventral valve usually displays a row of small slender spines, which 
become gradually longer towards the angles. The area and foramen 
are similar to those of Strophomena, as are also (very nearly) the 
muscular impressions and divaricator process of the dorsal valve. 
The valves articulate by teeth and sockets, and in one species (C. 
hemispherica) the area of the ventral valve is striated. 
Between twenty-five and thirty species have been described as 
occurring in the Devonian rocks in the neighbouring States, and it is 
thus almost certain that the four or five which occur in Canada include 
no form that has not been named. At present, I can identify only 
one. 
CHONETES HEMISPHERICA.—(Hall). 
CHONETES HEMISPHERICA X C. arcuaTa.—Hall. Tenth Annual 
Report of the Regents of the University of New York, p. 116-117. 
Fig. 121. Fig. 122. Fig 128. 
Fig. 121.—Chonetes hemispherica, drawn from the largest specimen seen. Fig. 122.—View 
of the ventral valve. A portion of the ventral area, shewing the striation and the 
bases of five species. Since this figure was engraved, other specimens have been pro= 
cured, shewing seven and eight spines. Fig. 123.—Longitudinal section, shewing the 
curvature of the ventral valve. [The dotted line representing the dorsal valve; conjec- 
tural, the valve not having been seen. | 
