288 
AUG. F. FOERSTE 
men the lateral diameter of the siphuncle appears to be 30 mm. 
Below the oblique crack at the base of the figured part of the 
specimen there is an unfigured part showing distinctly the dorsal 
outlines of 3 segments of the siphuncle. As far as can be deter- 
mined, the width of the siphuncle here is 32 mm. where the 
lateral diameter of the conch is 48 mm. Unfortunately it is 
impossible to determine with certainty whether the location of 
the siphuncle is central or marginal, although I am inclined to 
regard it as submarginal, extending to within 1 mm. of the ven- 
tral wall of the conch, and with its nummuloidal segments oblique 
to the vertical axis. The vertical outline of the segments of 
the siphuncle, the distance between consecutive annulations of 
the siphuncle, the length and curvature of the septal necks, 
the adnation of the septa to the lower side of the annulations, 
all are similar to those of Actinoceras tenuifilum. 
The surface of the shell is marked by low and rather broad 
transverse striae which tend to be sub-parallel to the sutures of 
the septa, especially along the broad median parts of the ventral 
side of the conch; but ventro-laterally, where the sutures slope 
more rapidly downward, the course of the transverse striae is 
slightly less oblique than that of the sutures. At or immediately 
above the sutures one of the striations tends to be slightly more 
conspicuous. 
Locality and Horizon. — From some unknown locality, pro- 
bably of Black River age, either on Boothia Felix or on King 
William Land. In the Palaeontologisk Museum, Kristiania, 
Norway. Collected by Lieut. Godfred Hansen in 1903-04. 
Remarks. — The downward 'curvature of the sutures of the 
septa on the ventral side of this specimen probably is shared 
with all species in which the siphuncle is marginal or submarginal, 
though the degree and angularity of this downward deflection 
may vary in different species. It is regarded as. related more 
nearly to Actinoceras tenuifilum than to any other described 
species, but a better knowledge of the siphuncle is needed in 
order to determine its relationship with some degree of confi- 
dence. It may be a new species but in the absence of definite 
knowledge of its siphuncle it can not serve as a type. 
