64 TRANSACTIONS OF THE ROYAL CANADIAN INSTITUTE. [VOL. XI 
point is 57 mm. This fragment shows the lines of growth on the carina 
to curve gently forward, while on the outer aspect of the whorl they 
are inclined backwards. Unfortunately the direction of these lines on 
the upper side of the whorl is not revealed. The outer aspect of the 
whorl, besides the lines of growth, carries seven revolving striz. 
In my original description (op. cit.) it is stated that the whorls are 
seven in number; a more detailed examination and a reconstruction 
indicate that they probably did not exceed four. 
Besides the lines of growth the impression of the alation shows 
delicate, close-set lines running forward and outward; I interpret these 
marks as due to the presence of tubuli in the alation, and I have indicated 
their direction on the lower portion of the figure. These markings 
would not be visible on the exterior of the shell. 
The generic position of this remarkably fine shell is of course some- 
what doubtful, as the character of the aperture is not revealed. The 
low-set and wide alation with tubuli arching forward and outward as 
well as the general shape of the whorl correspond with Euomphalop- 
terus as defined by Ulrich, but the open character of the coils proper 
and their restricted number seem to be departures from the generic type. 
I am informed by Mr. Tyrrell that he observed numerous examples 
of this gigantic gastropod along the Severn river. It seems fitting that 
this, the most remarkable fossil of the collection, should bear Mr. Tyr- 
rell’s name. . 
Locality—Limestone rapids, Severn-river, District of Patricia, Ontario. 
Horizon—Silurian. 
No. 344 S. Royal Ontario Museum of Palaeontology. 
EUOMPHALOPTERUS cf. VALERIA, Billings sp. 
PLEUROTOMARIA VALERIA, Billings. Geol. Sur. Can., Palaeoz. Foss., Vol. I, p. 169, 1865. 
PLEUROTOMARIA VALERIA, Whiteaves. Geol. Sur. Can., Palaeoz. Foss., Vol. III, p. 23, 
pl. 4, figs. 1 and 1a, 1884; Ibid., p. 71, pl. XI, figs. 2, 3. 
EUOMPHALOPTERUS VALERIA, Whiteaves. Geol. Sur. Can., Palaeoz. Foss., Vol. III, p. 339. 
EUOMPHALOPTERUS VALERIA, Parks. Bur. Mines of Ont., 22nd Rep., pt. I, p. 196, 1913. 
This species is represented by a single, well preserved cast of the 
interior. The specimen is about 53 mm. in maximum diameter, and 
agrees so closely with Whiteaves’ figure that it must be ascribed to 
Euomphalopterus valeria, although the determination of species from 
internal casts is necessarily hazardous. It should be noted (op. cit.) 
that Whiteaves considers that E. valeria is probably the same as E. 
alatus, Wahlenberg. A second specimen from the same locality is 
