THE DEVONIAN FOSSILS OF CANADA WEST. 257 
size from the middle of the shell outwards, the grooves between them 
rounded. Surface usually smooth, but when well preserved, with 
fine concentric striz. The mesial sinus is represented by the middle 
furrow of the ventral valve, and the fold by the middle rib of the 
dorsal. 
The ordinary width of this species is ten or twelve lines on the 
hinge line, but some are sixteen lines. In a specimen of this latter 
size the area of the dorsal valve is scarcely half a line high, and that 
of the ventral valve two-thirds of a line. The former lies nearly in 
the plane of the margins of the shell, while the latter slopes a little 
outwards. The beak of the ventral valve is incurved so as to project 
a little over the plane of the area, and its point is within half a line 
of the umbo of the dorsal valve. 
This species may be easily distinguished from S. mucronata and S. 
varicosa, by the form of the ribs, which are round instead of angular, 
twice the size of those of the other species, and separated by rounded 
grooves. The mesial groove or sinus is only slightly larger and more 
conspicuous than those next it on each side. 
Locality and Formation.—Rama’s Farm near Port Colborne. Near 
Woodstock. 
Collectors.—A. Murray, E. Billings. 
SprRIFERA FIMBRIATA.—(Conrad ) 
DettTHyris FimBRiaTa.—Conrad. Journal of the Academy of Nat- 
ural Sciences of Philadelphia, Vol. VIII., p. 263. 
Fig. «8. Fig. 69. Fig. 70. 
Fig. 68 Spirifera fimbriata—Conrad. Dorsal view. Fig. 69. Side view. 
Fig. 64. Ventral view. 
Description.—Transversely oval ; hinge line shorter than the great- 
est width of the shell ; cardinal angles rounded ; mesial fold and sinus 
moderately rounded ; from three to eight obscure ribs on each side; — 
