id 
THE DEVONIAN FOSSILS OF CANADA WEST. 271 
prominent ; on each side of the fold there are also six, their extremities 
strongly curved towards the ventral valve. 
I have seen no specimens with the true surface of the shell pre- 
served. 
Length of specimen upon which the above description is founded, 
nine lines, greatest width at about one-third the length from the front, 
ten lines ; depth of both valves at the front, six lines ; width of mesial 
fold at front, five lines, and of the sinus, five lines and a half. 
Judging from the appearance of several imperfect specimens, the 
depth of both valves at the front must be very variable. 
I have seen some small specimens from four to six lines in length, 
with a beak nearly erect. These, I think, are the young of R. Tethys. 
Locality and formation.—Cownty of Haldimand. Corniferous Lime- 
stone. 
Collector.—J. De Cew. 
RHYNCONELLA MeprA.—N. Sp. 
Desecription.—Oval or sub-triangular, body of shell, excluding the 
beaks, transversely sub-elliptical ; greatest width a little below the 
middle ; apical angle, about 100° ; both valves rather convex. Ventral 
valve with a neatly defined, rounded umbo, and closely incurved beak ; 
a wide, shallow, concave, mesial sinus, which becomes obsolete at 
about two-thirds the length from the front. Dorsal valve, with a broad, 
depressed, convex, mesial fold, extending two-thirds the length of the 
shell, umbo rather prominent, obtusely rounded, beak incurved beneath 
that of the ventral valve. Surface with between thirty and thirty-five 
small sub-angular ribs on each valve ; ten on the mesial fold, and nine 
in the sinus, 
Length, eleven lines. Width, twelve limes. Depth, seven lines ; 
width of sinus at front margin, six lines. 
The specimen is a little distorted towards the front, so that all the 
details of the outline cannot be given. ‘The sides diverge from the 
beak at an angle of about 100°, and are straight for half the length of 
the shell. They then appear to be somewhat narrowly, but regularly, 
curved round to the front, which is also, I think, broadly rounded. . 
LIneality and formation.—Township of Rainham, Concession 3, 
Lot No. 2. 
Collector.—J. De Cew. 
