GEOLOGICAL SURVEY, CANADA

Paratrachyceras aylardi n. sp. Pl. VIII, figs. 1, 2. Fairly evolute, compressed,
rounded ventro-lateral shoulder, ventral sulcus, no keels, well rounded umbilical shoulder.
Coarse ribs attenuated and well projected on ventro-lateral shoulder. Smaller, with coarser
ribs, more strongly projected and ventrally attenuated than in Paratrachyceras richthofeni

Mojsisovics. G. S. C.:; hol., 9549.

Asklepioceras delicatum n. sp. Pl. IV, figs. 6, 7. Moderately evolute, compres-
sed, broad venter, rounded ventro-lateral shoulder, narrow, deep ventral sulcus, rounded
umbilical shoulder. Numerous, narrow, almost flat, striated ribs separated by narrow fur-
rows, which are wider and deeper on the core than on the surface. About ten rows lateral
and ventro-lateral tubercles; two rows border ventral sulcus. More compressed, more nume-
rous furrows, more deeply cut on core than Asklepioceras glaciense McLearn. G. S. C.:

hol., 9550.

Asklepioceras mahaffii n. sp. Pl. VI, figs. 1 to 3. A small stout-whorled moder-
ately involute species, broadly rounded ventro-lateral shoulder, very shallow ventral sulcus.
The small holotype shows stage of smooth to striate shell with distantly spaced furrows,
succeeded by stage of slender ribs, projected on ventro-lateral shoulder and extending
across the very shallow, ventral sulcus. No tubercles. Differs from Asklepioceras laurenci
McLearn in presence of mature fine-rib stage. G. S. C.: hol., 9551; par., 9552.

Ottawa, Canada,
December, 1947.

PAPER 47-24