GEOLOGICAL SURVEY, CANADA PAPER 47-24
APPENDIX. New species from the Triassic Nathorstites fauna, by F. H. McLearn.

Daonella elegans n. sp. Pl. IV, fig. 2. Longer than high; beak in advance mid-
dle hinge line. Costae, variable but always fine, wavy in places; change in direction cos-
tae on border umbones. Ornament somewhat like that of Halobia subcomata Kittl, but cos-
tae wavy in places, lacks Halobia anterior wing and relatively longer. G. S.C.: hol., 9537.

Osirea atsina n. sp. Pl. VII, fig. 11. Thin, curved shell, low umbones, mostly
higher than long. Mostly approximate, fine varices of growth, occasionally more promin-
ent. Flatter shell with less prominent umbones than Ostrea pictetiana (Mortillet) Stoppani.

G. S. C.: hol., 9538.

Pecten ? sarsiana n. sp. Pl. VII, figs. 3, 4. Higher than long to about as high
as long; fairly convex; large, not well differentiated ears; numercus radial costae in two or
three degrees of strength. More and finer costae than in Pecten ? dishinni McLearn.

G. S. C.: hol., 9539; par., 9540.

Pleuromya peacensis n. sp. Pl. VII, fig. 12. Elongate, fairly convex; beaks
about one quarter from anieiior end shell; post-umbonal slope narrowly rounded; irregularly
spaced varices of growth. Outline more narrowly rounded than in Pleuromya musculoides

Schlotheim. G. S. C.: hol., 9541.

Pleuromya triasina n. sp. PI. VII, figs. 8, 9. Somewhat subquadrate in outline,
but narrowing anteriorly; abruptly rounded post-umbonal slope; faint varices of growth.
Beaks more central than in Pleuromya peacensis n.sp. and outline not narrowed posteriorly.

G. S. C.: hol., 9542; par., 9543.

Nitanoceras leve n. sp. Pl. Ill, fig. 6. Larger and smoother species than Nitan-
oceras selwyni; constrictions only at antericr end; growth lines straight or concave across
venter. Suture line like N. selwyni, of which may be only variety. G. S. C.: hol., 9544.

Paratrachyceras tetsa n. sp. Fl. IV, figs. 3, 4; Pl. VIII, fig. 3. Moderately evo-
lute, compressed, broad ventral sulcus. Ribs at first of even size and evenly spaced, then
irregular and bundled. All ribs projected on ventro-lateral shoulder, ending in very small
tubercles. More compressed, more evolute and with simpler suture line than P. dichoto-

mum Munster and has stage irregular nbbing. G.S.C.: hol., 9545; par., 9546.

Paratrachyceras sutherlandi n. sp. Pl. V, fig. 9. Variably compressed, moder-
ately evolute, with narrow yenter, shallow ventral sulcus, angular ventro-lateral shoulder,
abruptly rounded umbilical shoulder. Fine, rather flat, ventrally projected ribs crossing
venter, but reduced there. Resembles P. regoledanum Mojsisovics as illustrated by Arth-
aber, but ribbing coarser and suture line simpler with fewer indentations. G. S. C.: hol.,

9547.

Paratrachyceras caurinum n. sp. PI. VII, fig. 13. Fairly evolute, compressed,
rounded umbilical shoulder. Ribs partly single, partly branching, strongly projected and at-
tenuated on ventro-lateial shculder, shght tendency to thicken at ventral end. Ribs vent-
rally more strongly piojected and more attenuated than in Paratrachyceras richfhofeni

Mojsisovics. G. S. C,: hol., 9548.