THE DEVONIAN FOSSILS OF CANADA WEST. 279 
largest specimen that I have seen is seventeen lines, the greatest 
width fourteen lines, depth eight lines. The smallest is about two 
Imes in length, and many of intermediate sizes have been observed to 
make out the series. It is not certain that this species belongs to 
the genus Athyris. 
Locality and formation.—County of Haldimand. Corniferous 
Limestone. 
Collectors.—J. De Cew, E. De Cew. 
Atayris (?) Ciusta.—w. Sp. 
Description.—EHlongate oval; greatest width at about one-fourth 
the length from the front margin; sides diverging at an angle of 
about 75° and somewhat straight, or gently convex, for rather more 
than half the length; front angles rounded; front margin nearly 
straight, or gently convex. Both valves depressed convex, smooth in 
the upper half, the front margin with four or five wide shallow con- 
cave indistinct folds or grooves which become obsolete at less than 
half the length. Beak of ventral valve erect, apparently a little 
incurved at the tip. 
Length five lines; greatest width at one-fourth the length from the 
front margin, three lines; depth of both valves at one-third the 
length from the beak, one line and one-fourth. 
The above description is founded on a single small specimen. I 
have seen a fragment of another that must have been, when perfect, 
seven lines in length, and I am inclined to think that the one de- 
scribed is a young individual of the species. 
This species differs from A. scitula, principally in being proportion- 
ally much flatter, and in having the front margin undulated by several 
obscure folds. 
Locality and formation.—Lot No. 45, Con. 1, Cayuga. Corni- 
ferous. 
Collector.—J. De Cew. 
Aruyris (?) unisuLcaTa.—(Conrad.) 
ATRYPA UNisvLCATA.—Conrad. Annual Report Geological Survey, 
New York. 1841, p. 56. 
RHYNCONELLA UNISULCATA.—Hauu. Tenth Annual Report of the 
Regents of the University of the State of New York. 1857, p. 125. 
