32 TRANSACTIONS OF THE ROYAL CANADIAN INSTITUTE. [VOL. XI 
ASCOCERAS BOREALE, Parks. 
Plate II, Figures 8 and 9. 
ASCOCERAS BOREALE, Parks, Bur. of Mines of Ont., 22nd Rep., pt. I, p. 192, 1913. 
The species is represented in the collection by one fairly well pre- 
served specimen, showing the general shape and the septal markings. 
The anterior prolongation or neck of the body chamber is broken off 
and the apex is slightly worn. 
The general form is sub-ovate and rather acuminate towards the 
apex when viewed from the dorsal or ventral aspects. Viewed from the 
lateral aspect the pointed apex is not observed, the outline being almost 
elliptical if the anterior prolongation of the chamber of habitation be 
disregarded. The greatest width is in advance of the mid-length and 
is 34. mm. dorso-ventrally and 55 mm. laterally, indicating a shell with 
considerable dorso-ventral flattening. The length from the anterior 
sigmoidal saddle to the apex is 46 mm., to which probably 2 mm. more 
should be added on account of the abrasion of the apex. 
A vertical section shows portions of two camera, the anterior of 
which is 1.5 mm. and the posterior slightly less. Camere further 
apicad are lost. The sigmoidal saddles are not preserved in the interior. 
The suture of the coalesced septa crosses the venter as a slight lobe: 
it then turns dorsal and orad until the two sides are within 12 mm. of 
each other on the dorsal side. A sharp inflection ventral and orad 
then occurs, with the septa still coalesced for a distance of 17 mm. 
Beyond this point four distinct dorsal saddles are indicated, showing 
intervals on the dorsum of 7 mm., 6 mm., and 3 mm. respectively from 
posterior to anterior. 
This species is of the general type of Ascoceras bohemicum, Barrande,} 
and it closely resembles A. costulatum described by Whiteaves from the 
Galena-Trenton of Black island, Lake Winnipeg.? Whiteaves’ form is 
larger, however, and is more rounded at the apex. The sutures of the 
sigmoidal saddles also appear to have a different course, as Whiteaves’ 
figure shows two sutures approximately parallel as viewed from the 
ventral side, whereas such an appearance would be impossible in our 
form. 
Ascoceras canadense, Billings’ is a comparable type, but our form is 
much less ventricose dorso-ventrally and the sutures of the sigmoidal 
saddles are united much more forward. A. anticostiense and A. new- 
berryi of Billings are not at all comparable. 
1 Systeme Silurian de la Boheme, pls. 93, 94 and 96. 
2 Geol. Sur. Can., Palaeox. Foss., Vol. III, p. 215, pl. XXII, fig. 1. 
3 Geol. Sur. Can., Rep. for 1853-56, p. 310; Ibid., for 1863, p. 218 with figure. 
