256 ROYAL SOCIETY OF CANADA 
runs back toward the posterior part of the valve. Extending forward 
from near the cardinal area on each side are the lateral ridges and the 
imprint of the vascular trunks, as in the ventral valve, but here more 
distinct and bearing a number of branches directed, some inward and 
some outward. 
Sculpture —The external surface of the valve of this species is marked 
by fine concentric lines, and fainter radiating lines; there are also at 
intervals, concentric growth lines, and less distinct undulations of the 
shell, radiating from the umbo. 
Size.—Dorsal valve. Length and breadth, each about 11 mm. The 
ventral valve is about 1°5 mm. longer. 
Locality.—McFees Point, George River, Cape Breton, collected by 
Messrs. Weston and Robert, of the Canadian Geological Survey. 
The plan of the muscular scars of this species is very nearly that of 
Obolus Quenstedti of A. Michwitz, found in Esthonia, Russia,! and as we 
find a shell in the Lower Cambrian of the St. John Group which possesses 
all the essential characters of an Obolus, but differs from this shell, we 
fully agree with Messrs. Hall and Clarke, that O. Quenstedti could, with 
propriety, be excluded from Obolus ; whether it should go into Lingulella 
will be better known when the internal features of the species Z. Duvisii, 
the type of that genus are more fully described. 
LINGULELLA ROBERTI, n. sp., Pl. L., Figs. 2a and b. 
Broadly ovate, the ventral valve acuminate, having a low mesian 
ridge in the posterior third, and shghtly upturned at the beak. The dorsal 
valve tumid posteriorly, with a narrow hinge-margin, the valve has a 
mesian grove in the posterior quarter, and is flattened toward the front. 
In the ventral valve the inner surface of the thickened posterior part 
of the valve carries two pairs of diverging ridges, the inner pair termin- 
ating at the scars of the anterior adductors, the outer pair of about equal 
length, but continuous with impressions of the curving vascular trunks. 
The dorsal valve also has in its interior four diverging ridges ; with- 
in the two outer ones at the back of the shell is the impression of the 
posterior adductor muscle ; and within the two inner ones, one-third from 
their ends, are the oval pits of the anterior adductors ; between these 
scars, and extending backward in the valve, is a faintly marked mesian 
ridge, placed about one-third from the posterior end of the valve. The 
pits of the anterior adductors diverge somewhat at their anterior ends, 
and a short distance in front of them are two small, round pits, near to- 
gether, which mark the points of attachment of the anterior adjustors. 
Sculpture. —This consists of irregular concentric striæ which inoscu- 
late with one another, producing a surface of broken ridgelets, similar to 

1 Genera of Palæozoic Brachiopods, Hall and Clarke, p. 337, figs. 38 and 39. 
