} 
» 
THE DEVONIAN FOSSILS OF CANADA WEST. 353 
ribs are also in general coarser, but occasionally specimens with fine 
bifurcating ridges are found exactly like those from the shaly lime- 
stone of the Helderberg mountains. 
Locality and Formation.—Oriskany Sandstone and Corniferous 
Limestone, County of Haldimand. 
Collectors.—K. Billings; E. De Cew; J. De Cew. 
LAMELLIBRANCHIATA.— (Blainville.) 
In the Oriskany Sandstone, Corniferous Limestone, and Hamilton 
Group of Canada West, we find about twenty species of lamellibran- 
chiate mollusca, mostly in a bad state of preservation. .These with 
several exceptions must remain for future examination. I shall only 
notice the following at present : 
Genus Cyrtoponta.—(Billings,) 1858. 
Cypricarpitrs.—Conrad. Annual Report on the Paleontology of 
New York, 1841, p. 51. 
Mereatomus.—Hall. Pal. N. Y. Vol. 2, p. 243. 1852. Not 
characterized. 
Cyrroponta.—Billings. Report of the Geological Survey of Canada, 
1858, p. 179. Sub-genus Vanuxem1a, p. 189. 
Patzarca + Mrecamponsa-—Hall. Twelfth Annual Report of the 
Regents of the University of New York, 1859, p. 10-13. Also 
Cypricarpinia !—Hall. Pal. N. Y. Vol. 3, p. 266. Not 
characterized. In part. Also Pantawarca and MrGamsponta in 
same work. 1861. 
Generic characters,—Kquivalve, imequilateral; umbones near the 
anterior end ; general form obliquely tumid, transversely sub-rhom- 
boidal, ovate or sub-cordiform ; posterior extremity larger than the 
anterior, which latter is often reduced to a small auriculate projection 
in front of the umbones; two muscular impressions, of which the 
posterior is superficial, and the anterior sometimes deeply excavated ; 
several linear anterior teeth crossing the hinge plate, backwards and 
obliquely downwards, usually curved and in some species striated, 
situated either beneath or a little in front of the umbones ; posterior 
teeth situated at or near the extremity of the hinge line, usually from 
two to five, elongate ; pallial line simple; some of the species with a 
narrow area between or behind the beaks. 
