THE DEVONIAN FOSSILS OF CANADA WEST. 255 
umbo of the dorsal valve, a space of one-fourth to one-half of a line 
intervening. Area of dorsal valve sub-linear or about one-third the 
height of that of the ventral valve. The whole surface, in well 
preserved specimens, is covered with zigzag concentric imbricating 
strize, from two to four in the width of one line. 
Width on the hinge-line from one to two inches, usually one inch 
and a half. Length from beak to front from eight to twelve lines. 
Locality and Formation.—Hamilton Group. Townships of Plymp- 
ton and Bosanquet. Also found loose, or in boulders in the drift in 
numerous localities in the extreme western Counties of the Provinces, 
Collectors—A. Murray. J. Richardson. Also from W. B. Wells, 
Esq., Judge C.C. Chatham, C. W. 
SPIRIFERA VARICOSA.—( Hall.) 
Spirirer varicosus.—(Hall.) Tenth Annual Report of the Regents 
of the University of the State of New York, 1857, p. 125. 
SPIRIFER SUBMUCRONATUS OR SUBATTENUATUS + S. INUTILIS.— 
(Hall.) Geology of Iowa. 
The species above quoted are all closely allied to each other, and 
also to S. mucronata. They differ from the latter in being in general 
a little smaller, and in having the umbo and beak of the ventral valve 
more prominent—the area of the same valve being consequently 
larger. 
In the corniferous limestone numerous fragments and single valves 
have been collected, which most probably belong to 8. varicosa, or to 
one or both of the others. I have referred them all to the former 
for the present provisionally, not being able to decide whether they 
are or are not identical therewith. At all events they must be most 
closely allied species. 
Some of them have the mesial sinus regularly concave, while in 
others it is divided by an obscure ridge along the middle. The mesial 
fold on the dorsal valve is sometimes marked by a central groove, but 
often it is entire. The individuals thus marked should probably be 
referred to S. bimesialis. (Hall.) Geol. Iowa. 
The following figures represent a specimen from the Corniferous, 
near Woodstock, with the length greatly less than the width and no 
median rib in the sinus. 
