1915] PALAEOZOIC FOssILS FROM HUDSON Bay. 43 
No septa, septal spines or pores are observable, even on polished sur- 
faces. 
Locality—Limestone rapids, Severn river; Limestone rapids, Fawn river, District 
of Patricia, Ontario. 
Horizon—Silurian. 
No. 306 S. (Severn river), No. 307 S. (Fawn river) Royal Ontario Museum of Palae- 
ontology. 
PETRAIA (?), sp. indet. 
A single badly crushed specimen presenting the following features: 
Corallum, straight, conical, 45 mm. long; width at top 27 by 14 mm., 
representing a probable diameter of about 20 mm. External surface 
shows transverse growth lines and well marked septal furrows. Septa 
probably about 65 in number. 
A vertical section shows nothing but crushed and broken septa 
which suggests the genus Petraia. Although the specimen is greatly 
flattened the preservation is sufficiently good to justify the conclusion 
that other internal structures are absent. This conclusion is strengthened 
- by the fact that the outer wall is little broken, although the specimen is 
crushed flat; this would indicate a lack of supporting structures in the 
interior. 
Locality—Limestone rapids, Severn river, District of Patricia, Ontario. 
Horizon—Silurian. 
No. 298 S. Royal Ontario Museum of Palaeontology. 
STREPTELASMA cf. ROBUSTUM, Whiteaves. 
STREPTELASMA CORNICULUM (?) Hall. Large and robust variety. Whiteaves, Geol. Sur. 
Can., Rep. Prog. for 1879-80, p. 57c. 1881. 
STREPTELASMA ROBUSTUM, Whiteaves. Can. Rec. Sci., Vol. VI, p. 391, 1896. 
STREPTELASMA ROBUSTUM, Whiteaves. Pal. Foss., Vol. III, pt. III, p. 153, pl. XVIII, 
AISy te LaelOO7. 
STREPTELASMA ROBUSTUM, Lambe. Geol. Sur. Can., Cont. Can. Pal., Vol. IV, pt. II 
p. 109, 1900. 
’ 
The specimen is very imperfect, but it indicates a Streptelasma of 
considerable size. The fragment is about 80 mm. long: it shows a strong 
curvature and a rapid expansion in diameter. At the top the diameter 
of the corallum is about 40 mm. The exterior is not shown, and the 
calyx is entirely broken away. A cross section shows about 70 primary 
septa, which reach close, if not quite to the centre. Secondary septa 
are absent or very slightly developed. Very numerous, close-set and 
inwardly arched dissepiments are seen in the interseptal loculi. A 
vertical section shows the strong development of dissepiments, which 
