262 THE DEVONIAN FOSSILS OF CANADA WEST. 
Width from one inch and a half to two inches. Length about five- 
sixths of the width. 
Locality and formation.—Lowe’s Mill, township of Bosanquet, 
Hamilton Shales. 
Collector.—The only specimen found was collected by C. Robb, 
Esq., C. E. 
SPIRIFERA SCULPTILIS P—(Hall.) 
The above figure represents an imperfect ventral valve (found by 
Mr. Robb along with S. Parryanus,) which appears to be identical 
with the species figured by Hall in the Geology of New York, Vol. 
IV., p. 202, under the name of S. sculptilis. 
Genus Cyrt1a.—(Dalman.) 
Generic Characters.—Shell semi-circular or triangular; ventral 
valve extremely prominent and of a pyramidal shape; area large, 
usually incurved ; foramen extending quite to the beak, closed except 
a small aperture near the beak by a convex deltidium. Dorsal valve 
flat or only moderately convex. The internal characters do not 
appear to differ greatly from those of Spirifera. 
The shells of this genus are smaller in general than Spirifera, and 
the species are closely allied to each other. 
Cyrtina is another genus exactly resembling Cyrtia in shape, but 
with the interior of the ventral valve divided by a mesial septum, 
which supports near the foramen a triangular chamber as in Penta- 
merus. 
Not having seen the interior of the two following species, I leave 
them in the genus Cyrtia where they have been hitherto placed. 
Cyrtia Hamittronensis —(Hall.) 
Cyrtia Hamittonensis.—Hall. Tenth Annual Report of the Re- 
gents of the University of the State of New York, p. 166. 1857. 
Description.—* Shell more or less obliquely triangular, pyramidal : 
hinge equalling the greatest breadth, and obtusely (or acutely) an- 
