1915] PALAEOZOIC FossILs FROM HupsoN Bay. 69 
TROCHUS (?), sp. indet. 
Plate III, Figure 7. 
Trocuus sp., Parks. Bur. Mines of Ont., 22nd Rep., pt. I, p. 194, 1913. 
This species is represented by a small and imperfect cast of a trochi- 
form shell, somewhat resembling Trochus gothlandicus, Lindstrém.' 
Ulrich regards this species as a derivative from Raphistominia and ex- 
presses great doubt as to the systematic position of the whole assem- 
blage of forms ascribed to Trochus by Lindstrém. That author himself 
is very doubtful as to these forms, and we may therefore regard these 
Silurian trochiform shells as of undetermined relations. Whatever 
may be the proper position of this type of shell, there is no doubt that 
they are well represented in the Silurian of Gotland, and that they are 
represented by two and possibly more species in our collection. Mur- 
chisonia hercyna, Billings, (M. billingsana, Miller) from the Guelph of 
Ontario is referable to the same general type. 
The present specimen shows portions of three whorls only; the lower 
one is about 14 mm. wide and 4.5mm. high. The apical angle is moderate 
(45°), the sutures but slightly impressed, and the outline of the whorl 
is almost straight from suture to suture. On one side the body whorl 
is much less inclined, but this feature may be due to deformation before 
the interior was filled with matrix. The specimen is quite indeter- 
minate specifically, but it is worthy of mention as typical of this trochi- 
form class of shells. 
Locality—Limestone rapids, Severn river, District of Patricia, Ontario. 
Horizon—Silurian. 
No. 367 S. Royal Ontario Museum of Palaeontology. 
TROCHUS (?), sp. indet. 
Plate III, Figure 14. 
One cast of a small trochiform shell about 11 mm. wide and practi- 
cally the same height. Volutions four or five. Probably imperforate. 
Apical angle 55 degrees. External face of whorls practically straight 
conforming to the shape of the shell. Base flat. 
The species is quite indeterminable, but the form is evidently 
related to the species described above; it represents a second variety 
of trochiform shell and may be compared with some of the species des- 
cribed by Lindstrém from the Silurian of Gotland. 
Locality—Limestone rapids, Severn river, District of Patricia, Ontario. 
Horizon—Silurian. 
No. 402 S. Royal Ontario Museum of Palaeontology. 
1Sil. Gast. and Pter. of Gotland, Lindstrém, Stockholm, 1884. 
