THE DEVONIAN FOSSILS OF CANADA WEST. 345 
cular, or sub-quadrate, usually rounded in front, cardinal angles either 
rounded or auriculate. Ventral valve ratheruniformly convex, cardinal 
angles compressed, rarely preserved, but when they are, a little 
reflected. Dorsal valve concave. Area of ventral valve half a line 
wide, lying in the plane of the lateral margin ; when perfect, longitu- 
dinally striated, or nearly smooth ; when a little worn, shewing obscure 
vertical strize ; edge of the area serrated. Area of dorsal valve half 
the width of the ventral, with a row of small tubercles on the outer 
edge, and a corresponding row of small pits on the inside. No fora- 
men. 
Internal surface of dorsal valve covered with small tubercles, usually 
about half a line apart; occlusor scars (in a specimen nine lines 
wide) situated one line from the hinge, each scar longitudinally 
divided by three elongated tubercles ; one line below each scar there 
is a prominent oval tubercle; half way between these are two others 
on the median line. The divaricator processes are two short stout 
projections. with their extremities notched, and the upper side 
grooved. I have not seen the interior of the ventral valve. 
This species is probably only a variety of S. Jepis, Bronn, of the 
Devonian rocks of Europe. It is easily recognized by its surface, 
which is destitute of radiating striz. 
Locality and Formation.—Corniferous Limestone, County of Hal- 
dimand. Township of Bosanquet, in the Hamilton Shales. 
Collectors. —E. De Cew, J. De Cew, J. Richardson. 
STROPHOMENA AMPLA.—(Hall.) 
STROPHOMENA AmpLA.—Hall. Tenth Annual Report of the Regents 
of the University of the State of New York, p. 112, 1857. 
Compare S. puNcTULIFERA.—Conrad, S. HEADLEYANA.—Hall, S. 
CAVUMBONA.—Hall, S. LEAVENWORTHANA.—Hall, and S. GENICU- 
LATA.—Hall, all in the 3rd Vol. of the Paleontology of New York. 
Description.—Shell, large; from two to three inches wide on the 
hinge line; length from two-thirds to four-fifths the width; ventral 
valve concave, with a gentle convexity in the region of the umbo ; 
often with a wide rounded mesial ridge, extending from the beak to 
the front margin. Dorsal valve convex, with a large, flat or gently 
concave space just in front of the beak; sometimes with a shallow 
rounded mesial sinus extending from beak to front. Area of ventral 
valve varying from one to three lines in width at the beak; varying 
Vou VI. 24 
