232 
'AUG. F. FOERSTE 
flatter than the dorsal. The lateral sides are rapidly rounded. 
The sutures form broad dorsal and ventral lobes. The lateral 
saddles are relatively high. Usually the conch is straight, 
though several specimens of Orthocevds hastatum are curved 
slightly lengthwise. In Hyatt’s generic description the conch is 
described as having the whorl arcuate in the young. 
30. TRIPTEROCERAS HASTATUM (BILLINGS) 
PLATE XXXI, FIGS. 3A, B, C, D 
Orthoceras hastatum Billings, Geol. Surv. Canada, Rep. Progr. for 
1853-56, published in 1857, p. 333 
Original Description : Shaped like a Theca, two-edged ; ventral 
side broad and almost flat, slightly convex; dorsal aspect most 
convex along the center, thence sloping to the sides, which are 
perpendicular to the ventral aspect, and nearly flat in the larger 
portion of the shell. The section is thus a low, broad-based tri- 
angle, with the angle at each end truncated, and with the apical 
angle rounded. At a lateral diameter of eleven lines the height 
or dorso-ventral diameter is six lines; the rate of tapering is 
about 4 lines to the inch, measuring the inclination of the sides ; 
the ventral and dorsal aspect approach each other at the rate of 
two lines and a-third to the inch; siphuncle small, close to the 
centre of the ventral margin ; the septa are curved in a circle of 
which the radius is about half-an-inch, their distance from each 
other has not been satisfactorily ascertained ; near the apex the 
sides consist of two rounded edges, but in the direction of the 
aperture these become more and more broadly truncated, until 
at a diameter of eleven lines they have a perpendicular width of 
about two lines. The surface is coarsely striated transversely, 
and, at the dorsal ridge, the striae appear to make a bend toward 
the aperture. 
Locality and Formation. — Black River and Trenton limestone, 
Pauquette’s Rapids, Ottawa City. 
Five specimens, numbered 1281, and lettered a, b, c, d, and e 
respectively, are in the Victoria Memorial Museum. Of these, 
specimen 1281a is regarded here as the type, since it is 11 
lines wide; a septum truncates its upper end. Specimen 1281c, 
with a septum at its lower end, comes next in size. Specimen 
1281d, here figured, shows the lengthwise curvature at its apical 
end, with the concave curvature on its dorsal side; it is ter- 
