74 TRANSACTIONS OF THE ROYAL CANADIAN INSTITUTE. [VOL. XI 
siphuncle and they seem to terminate towards the centre of the rings. 
Although there is no direct evidence that the tubuli communicated 
with the camere I have every reason to believe that such was the 
case by comparison with another example of the species (vide postea). 
This species is of the type of Orthoceras (Actinoceras) crassiventre, 
Wahl. as figured by Barrande in Plate 233, Systéme Silurien de la 
Bohéme. It differs in the much greater width of the siphuncle for a 
given height of segment. Actinoceras hearsti is also closely related to 
a species from the Trenton of Manitoba ascribed by Whiteaves to 
A. richardsoni and figured in Volume IX, Section IV, Transactions of 
the Royal Society of Canada. The Royal Ontario Museum contains 
specimens of this form which have been cut and polished; they resemble 
Whiteaves’ figures, but they show neither the calcareous lamellae or 
the direct tubuli characteristic of A. richardsoni. The species is named 
for the Honourable W. H. Hearst, Premier of Ontario, on whose initia- 
tive the Hudson Bay Exploring Expedition of 1912 was organized. 
Locality—Limestone rapids, Severn river, District of Patricia, Ontario. 
Horizon—Silurian. 
No. 314 S. Royal Ontario Museum of Palaeontology. 
ACTINOCERAS, sp. nov. 
Plate II, Figure 3. 
AcTINOCERAS sp., Parks. Bur. Mines, Ont., 22nd Rep., pt. I, p. 196, 1913. 
The specimen consists of two siphuncular rings, very different from 
any others in our collection and from any figured by Bigsby or Stokes. 
The segments are elliptical with a greater diameter of 55 mm. and 
a shorter diameter of 45 mm. On the inner side the rings are evenly 
rounded and 11 mm. thick; on the outer side they are much flattened 
posteriorly and have a thickness of 13 mm. This flattening of the 
rings indicates a marginal position for the siphuncle, and the greater 
thickness may indicate a curved shell with the siphuncle on the convex 
side. The rings are inclined at an angle of more than 45 degrees to 
the axis of the siphuncle; this could occur only in a shell with septa 
arched forward to a remarkable degree. 
The endosiphuncle seems to have been a distinct tube, 12 mm. 
wide and apparently possessed a proper wall. 
This form is unique in our collection and apparently represents an 
undescribed species, I hesitate, however, to give it a specific | name in 
view of the very incomplete nature of the specimen. 
Locality—Assina rapids, Severn river, District of Patricia, Ontario. 
Horizon—Silurian. 
No. 313 S. Royal Ontario Museum of Palaeontology. 
