352 THE DEVONIAN FOSSILS OF CANADA WEST. 
Fig. 126.—Leptocelia flabellites—Dorsal and side views. 
Description.—Shell semi-elliptical, or sub-circular, or transversely 
oval. Dorsal valve nearly flat, with from ten to fourteen rounded or 
sub-angular ribs, one or two of which, in the middle, are usually 
separated from those on each side by grooves deeper and wider than 
the others and sometimes depressed so as to give the appearance of a 
mesial sinus ; hinge-line either nearly straight or with the portions 
on each side of the beak forming an obtuse angle seldom so acute as 
150°. Ventral valve moderately convex, often carinate along the 
middle, beak small, pointed, incurved down to the dorsal area ; ribbed 
like the opposite valve. 
Width from six to ten lines. Length a little less than the width. 
Locality and Formation.—Oriskany Sandstone and Corniferous 
Limestone, County of Haldmand, Canada West, also in prodigious 
numbers in the Oriskany Sandstone at Gaspé, Canada East. 
Collectors.—A. Murray; E. Billings; E. De Cew; J. De Cew, in 
Canada West. Sir W. E. Logan; J. Richardson; R. Bell, Gaspé. 
LEeproca@Lia ConcAvA. Hall. 
Fig. 127. 
Fig. 127.—Leptocelia concava. Ventral, dorsal and side views. + 
Description.—Ovate or nearly circular; length three or four lines ; 
width equal to, or a little less than the length. Ventral valve convex 
sub-carinate along the middle. Dorsal valve flat or often concave. 
Surface with from ten to fourteen rounded radiating ribs. 
This species closely resembles the L. flabellites but is never more 
than half the length or width. On comparison with specimens of 
LL. concava from the Lower Helderberg of New York, I find so little 
difference that I do not see how those of the Corniferous Limestone 
are to be separated. In several the dorsal valve is not so deeply 
concave as it is in those from the lower rock, but in others it is. The 
