THE DEVONIAN FOSSILS OF CANADA WEST. 329 
In the class ConcuireRA, we have representatives of the genera 
Unio, Anodon, and. Cyclas. 
Genus Unro,—1. U. nasutus; very common on the Island. 2. 
U. ochraceus: 3. U. complanatus, also from the Island, A few 
more species or varieties can be obtained at the Island and Weston. 
Considerable difficulty is encountered in the naming of Unios, from 
the immense number of species, and the want of proper works of 
reference, 
Genus ANopon :—Several varieties of this genus are to be found 
—principally at the Island. 
Genus Cycias:—This genus is very common. The specimens 
obtained probably comprise several species, but their characters are 
too minute and inconspicuous to admit of any definite determination. 
ON THE DEVONIAN FOSSILS OF CANADA WEST. 
BY E. BILLINGS, F.G.S. 
(Continued from Vol. VI. page 282.—No. XXVIII. May, 1860.) 
Genus SrropHomeNA.—(Rafinesque. ) 
SrropHoMENA.—(Rafinesque.) De Blainville. Manuel de Mala- 
cologie, p. 513, Pl. 53, fig. 2, 2a, 1825. Davidson. Introduction 
to the Classification of the Brachiopoda. p. 106. 
Lepr2na.—Dalman, and many other authors. 
Leprana. + SrropHomena + SrropHoponta, either wholly or 
in part, of Hall and American authors. 
Generic characters.—Shell, semicircular, semioval, sub-quadrate or 
sub-triangular, with the hinge line straight ; one valve convex and 
the other concave ; in a few species both valves nearly flat. Both 
valves provided with an area, that of the ventral valve usually the 
larger. Area of ventral valve with a triangular or linear foramen or 
fissure in the middle beneath the beak, either wholly or partially 
closed by a deltidium; in some species no foramen. Area of dorsal 
valve often with a triangular projection in the middle, caused by the 
protrusion of the bases of the divaricator processes ; in some species 
Vou, VI. Z 
