84 TRANSACTIONS OF THE ROYAL CANADIAN INSTITUTE. [VOL. XI 
A somewhat similar form from the Attawapiskat river was described 
by Whiteaves as P. lineolatum! but our specimens differ strongly in 
the convex instead of concave outline of the ventral margin of the living 
chamber. 
A much closer resemblance is presented to P. parvum, Hall and 
Whitfield ;? not so much to the type figure as to later drawings, e.g., that 
by Whiteaves (PI. VII, Fig. 2, Vol. III, Pal. Foss.) and those by Clarke 
and Ruedemann (Guelph Fauna in the State of New York, Mem. 5, 
N.Y. State Museum, pl. 21, figs. 1-8.) The sharply drawn out, ventral 
apertural tube, which is considered typical of P. parvum, as well as the 
general shape of the body chamber, is common with our species. On 
the other hand, P. parvum does not show the sharp curvature of the 
septate region, which is a striking feature of the new species. 
Locality—Drift, near mouth of Seal river, Nelson river, District of Patricia, Ontario. 
Horizon—Doubtful, but probably Silurian. 
No. 316 S. Royal Ontario Museum of Palaeontology. 
Two slabs of whitish-grey fine grained argillaceous limestone from 
the drift at York. The stone is full of impressions and casts of Ostra- 
coda. The recognizable species are as follows: 
ISOCHILINA GRANDIS LATIMARGINATUS, Jones. Geol. Sur. Can., Cont. to Can. Micro- 
Pal., Vol. I, pt. 3, p. 78, pl. 10, figs. 1a, b and 
c, and 3 and 4, 1891. 
No. 421 S. Royal Ontario Museum of Palaeontology. 
LEPERDITIA WHITEAVESII, Jones. Geol. Sur. Can., Cont. to Can. Micro-Pal., Vol. I, 
pt. 3, p. 87, fig. 6, p. 87, pl. 12, figs. 11, 12, T3)andjaay 
18901. ; 
No. 422 S. Royal Ontario Museum of Palaeontology. 
LEPERDITIA HISINGERI, Schmidt. Mem. Acad. Imp., St. Petersbourg, ser. 7, Vol. XXXI, 
no. 2, p. 16, figs. 22 and 23, 1873; Ibid., Vol. XXXI, no. 5, 
p. 14, pl. V, figs. 5-7, 1873. 
LEPERDITIA HISINGERI, Jones. Geol. Sur. Can., Cont. to Can. Pal., Vol. I, pt. 3, p. 82, 
pl. 10, figs. 5 and 7; pl. 12, figs. 8 and 15; pl. 13, figs. I, 2, 3, 
4, 5, and 9. (See this article for extended synonomy.) 
No. 420 S. Royal Ontario Museum of Palaeontology. 
The slab contains several casts of Leperditia referable to the last species, 
but probably to be ascribed to some of the varieties described by Jones 
(op. cit.). L. hisingeri fabulina is probably present with others of 
Jones’ varieties. 
There can be little doubt that these slabs were derived from a Silurian 
horizon very similar to that at the north end of Lake Winnipegosis, 
Cedar lake and the Grand rapids of the Saskatchewan. 
1 Geol. Sur. Can., Palaeoz. Foss., Vol. III, pt. IV, p. 265, pl. 34, figs. 1, la, 2 and 3, 
1906. 
2 Pal. of Ohio, Vol. 2, p. 151, pl. 8, fig. 10, 1875. 
