348 THE DEVONIAN FOSSILS OF CANADA WEST. 
Limestone, and Hamilton Group, constitute but one species. The 
only variation that could be regarded as of specific importance are 
those of the area of the ventral valve above mentioned. In four of 
our specimens it forms a right angle to the plane of the lateral mar- 
gin. In several others it forms an angle of about 120°, and taking 
these extremes it might well be thought that there are two species. 
But we have one fine specimen in which the angle is about 100°. I 
therefore think that this is not a variation of specific value. 
In all the more general characters this species is precisely identical 
with S. punctulifera, (Conrad) and those allied therewith, which I 
have cited above from the 3rd vol. of the Pal. N. Y. The corniferous 
specimens are, upon an average, larger than those figured by Prof. 
Hall from the Lower Helderberg. This, however, of itself would 
not be of specific value. The only doubt I have as to the identity of 
this species with S. punctulifera rests upon the characters of the 
foramen of this latter. It is (at the time of writing this) not figured, 
but Prof. Hall thus describes it: ‘‘ Foramen nearly closed, with a 
narrow prominent callosity along the centre.’ In S. cavumbona, he 
says, ‘‘ Foramen small, narrow, closed by a callosity.”’ In S. Head- 
leyana, “ Foramen narrow, closed.” In 8S. Leavenworthana, “ Fora- 
men small, triangular, closed in full grown individuals.” As there 
thus appears to be some difference, I strongly suspect that a series” 
might be made out showing a gradation in the size of the aperture 
in all the above named species. In such poor specimens of the Lower 
Helderberg species as I have before me, the foramen cannot be 
observed at all. The surface characters and the form seems to me to 
be the same, and for the present it should be left an open question 
whether or not S. ampla is distinct from S. punctulifera. 
Locality and Formation.—County of Haldimand, in the Oriskany 
Sandstone and Corniferous Limestone, Township of Bosanquet, in 
Hamilton Group. 
Collectors.—A Murray, J. De Cew, E. De Cew, E. Billings. 
STROPHOMENA MAGNIFICA.—(Hall). 
This is a large, nearly flat species, three or four inches wide. It 
resembles 8. perplana. Our specimens are all very imperfect. It 
occurs in the Oriskany Sandstone, County of Haldimand. 
