[MATTHEW ] OROOVICIAN SYSTEM ON THE ATLANTIC COAST 255 
In the Island of Cape Breton the rocks of the shore of Bras d'Or 
Lake, near Barrosois Brook, consist of various alternations of sandstones 
’ 2 
‘ Some of the shales, away from the shore, on the 
slates and shales. 
Barrosois or McLeod Brook, contain Dictyonema flabelliforme, and are 
therefore Upper Cambrian. The coarser beds on the shore of -Bras d'Or 
Lake which contain the fossils described below are more modern, as will 
appear by the following review of their fossil contents. 
In the following description the fossils are arranged according to 
their zoological standing. 
LINGULID E. 
LINGULELLA, Salter. 
In the collections examined there are two species that may be referred 
to the above genus, although the impressions of the sliding muscles are 
more external than Mr. Salter has declared to be the case in the Welsh 
species, L. Davisii, the type of the genus. The Canadian species were 
collected in Cape Breton and occur in a calcareous sandstone which has 
suffered from dynamical movements, and the fossils are all considerably 
distorted : the figures of the species are adjusted for this distortion. 
LINGULELLA SELWYNI, n. sp., Pl. I., Figs. la and b. 
The form is sub-ovate, broadly rounded in front, but having nearly 
straight sides in the posterior half ; the beak of the ventral valve is regu- 
larly pointed and that of the dorsal bluntly rounded. 
The ventral valve in its interior, exhibits two large, triangular scars, 
where the central muscles were attached, one on each side of the rhombic 
pit in the posterior third of the valve. The posterior adductors appear 
on each side of the hinge area, and there are sliding muscles exterior to 
and in front. of them. In front of the posterior adductor muscle, on each 
side of the valve, there is a low ridge extending forward as far as the 
scars of the central muscles: at and in front of these ridges the imprint of 
the main vascular trunks is visible, extending forward toward the median 
line. 
The interior of the dorsal valve has a broad scar (posterior adductor ?) 
Just in front of the striated hinge area, and on each side of the hinge are 
impressions of sliding muscles. The central muscles are indicated by a 
group of small pits near the centre of the valve; of these the anterior 
adductors are oval and somewhat apart at the mid-length of the valve ; 
the anterior adjusters are indicated by a pair of small rounder pits, a 
little in advance of those last named and closer together. A faint line 
(indicating the border of the splanchnocæle ?) includes these scars and 

1 Geol. Surv. Can. Rep. Pree, 1875-6 (Fletcher's Report), p. 389. 
