AECTIC ORDOVICIAN AND SILURIAN CEPHALOPODS 261 
spire, but at its base it exposes a short part of the length of the 
two lower volutions. 
Locality and Horizon. — From the Orthoceras limestone at 
Victoria Head on Bache peninsula, in Ellesmer eland, west of 
Smith Sound. The horizon is regarded as of Canadian age. 
In the Palaeontologisk Museum, Kristiania, Norway. Collected 
by Per Schei in May, 1899, on the Second Polar Voyage of the 
^‘Fram’^ under Captain Sverdrup. 
Remarks. — Since typical Euconia is of Canadian and Chazyan 
age it would be interesting to discover this genus in the Orthoceras 
limestone of Victoria Head. In its apical angle and in the large 
size of its open umbilicus the species here figured and described 
resembles the vertical section of Pleurotomaria {Euconia^.) 
quehecensis figured by Billings, but here the resemblance ends. 
The Victoria Head specimen has an extremely thin shell, there 
is no trace of lines of growth or of a slit-band, and the inner 
outline of the volutions is much more angular. 
2. Clarkoceras holtedahli Sp. nov. 
Plate XXVII, figs, 2A, B; Plate XXXIII, fig, 1 
Specimen consisting chiefly of the upper part of the phragma- 
cone; to this is attached that part of the basal portion of the 
living chamber which is adj acent to the siphuncle. The phragma- 
cone is estimated to have had a height of at least 60 mm. 
The dorso-ventral diameter at the base of the living chamber 
is estimated at 47 mm., and the dorso-ventral apical angle was 
between 35 and 40 degrees. The conch is strongly compressed 
laterally, the lateral diameter at the base of the living chamber 
being, estimated at 25 mm. The conch is slightly curved length- 
wise in a dorso-ventral direction. The location of the siphuncle 
is endogastric, or on the concavely curved side of the conch. 
Here the curvature equals about 1 mm. in a length of 25 mm. 
The opposite side of the conch is curved in a convex direction, 
apparently at about the same rate as the concavely curved side. 
Five camerae occupy a length of 16 mm., measured along the 
lateral side of the specimen; 2 additional camerae of about the 
