34 TRANSACTIONS OF THE ROYAL CANADIAN INSTITUTE. [VOL. XI 
II 
ORDOVICIAN SPECIES FROM THE DRIFT 
The following species were collected from the superficial deposits 
chiefly from near the mouth of the Shamattawa river. Most of the 
specimens represent a fauna similar to that at the lower rapids, but 
one specimen seems to indicate a higher horizon comparable with the 
Cincinnatian. 
Cf. RAFINESQUINA ALTERNATA, Emmons sp. 
STROPHOMENA ALTERNATA, Emmons, Geol. Sur., N.Y., Rep. 2nd Dist., p. 395, fig. 3, 
1842. 
One cast of the convex valve resembling this species, but impossible 
of certain identification. 
Locality—Drift, mouth of the Nelson river, Manitoba. 
Horizon—Ordovician probably. 
No. 406 S. Royal Ontario Museum of Palaeontology. 
WHITELLA, sp. tndet. 
Plate IV, Figure 15. 
One imperfect cast of the interior of a left valve. The shell is about 
43 mm. long and possibly 28 to 30 mm. high, but the ventral margin is 
not preserved. In the drawing this margin has been restored in a dotted 
line. The beaks are very prominent and incurved. The umbonal ridges 
are well developed and there is a defined depression dorsal to the beak 
extending forward, possibly to the extreme anterior margin of the shell. 
All these characteristics are typical of Whitella, and I have little doubt 
that the specimen belongs in this genus: it is too imperfect to justify 
a specific description. 
Locality—Mouth of Shamattawa river, Manitoba (Drift). 
Horizon—Ordovician. 
No. 423 S. Royal Ontario Museum of Palaeontology. 
ISOTELUS, sp. indet. 
One fragment of a large species of Jsotelus. The eight thoracic 
rings show a length of about 60 mm. Small portions of the buckler and 
of the pygidium are preserved, but all distinctive characteristics are 
obliterated. This specimen is probably referable to J. gigas, De Kay. 
Locality—Drift at Limestone rapids, Severn river, District of Patricia. 
Horizon—Ordovician. 
No. 425 S. Royal Ontario Museum of Palaeontology. 
