THE DEVONIAN FOSSILS OF CANADA WEST. 271 
Genus CENTRONELLA.—(Billings.) 
CENTRONELLA.—Billings. Canadian Naturalist and Geologist, 
Vol. IV., p. 131. April, 1859. 
Generic characters.—Shells, having the general form of Terebratula. 
Dorsal valve with a loop consisting of two delicate riband-like lamelle, 
which extend about one-half the length of the shell. These lamellz 
at first curve gently outwards, and then approach each other gradually, 
until at their lower extremities they meet at an acute angle; then 
becoming united they are reflected backwards towards the beak, in 
what appears to be a thin, flat, vertical plate. Near their origin each 
bears upon the ventral side a single triangular crural process. 
This genus appears to stand between Terebratula and Waldheimia. 
In the former, the loop is short, not exceeding greatly one-third the 
length of the shell, and not reflected. In the latter, it extends nearly 
to the front, and is reflected, but the laminze are not united until they 
are folded back. 
CENTRONELLA GLANS-FAGEA.—(Hall.) 
RHAYNCONELLA GLANS-FAGEA.—Hall. Tenth Annual Report of the 
Regents of the University of the State of New York, p 125. 1857. 
Fig. 97. 
Fig. 97.—Centronella glans-fagea. Three views of a specimen of the usual size. These 
figures are too much rounded at the sides. 
Description.—Shell smooth, ovate or sub-rhomboidal, greatest 
width about the middle, from which point the sides are nearly straight 
in the upper half, and converge to the beak at an angle of about 859 ; 
front half rounded, sometimes with a sinus in the front margin. 
Ventral valve the larger, its outline forming a nearly regular arch 
from the beak to the front margin, strongly and broadly sub-carinate 
along the middle in the larger individuals, more uniformly convex in 
the small ones ; beak long, strongly incurved over the dorsal valve, 
but not in contact therewith. Dorsal valve nearly flat, with a wide, 
shallow, mesial sinus, which, in some specimens, occupies nearly the 
whole width of the shell, but in others it is almost obsolete, and the 
