OREOHELIX CARINIFERA, n. sp.
The shell is lenticular, carinate, umbilicate, the width of umbilicus
between a fourth and a fifth that of the shell, whorls 4½, slowly
increasing, the first 2½ strongly convex, obliquely striate, the striae
finer on the embryonic portion. Subsequent whorls are strongly
convex around the upper (inner) part, becoming concave near the
outer edge; the striation is rougher, and some weak traces of spiral
striae appear in places. The last whorl is noticeably concave above
and below the peripheral keel; it descends very slightly or not at
all in front, and on the base there are very inconspicuous, well
spaced spirals composed of granules. The oblique alt. and the
diameter of the aperture are equal, and there is a slight angle at the
termination of the keel.
Alt. 5, diam. 9.4 mm.; width of umbilicus 2 mm.; oblique alt. and
diam. of aperture 4 mm.
Garrison, Montana. Type and paratypes No. 99253 A. N. S. P.
Oreohelix alpina Elrod, which comes from high elevations (8,500
9,000 ft.) in the Mission Mountains, is about the size of this snail,
but the whorls are less convex, the convexity of the later ones is
simple, while in carinifera there is a concavity above the periphery.
O. alpina has no spiral sculpture or granulation, and the keel is less
pronounced. I regard such similarity as exists as due to convergence rather than to actual relationship. 0. hemphilli Nc. differs in
the sculpture and shape of the embryonic whorls.
O. carinifera is one of the smallest Oreohelices, the dimensions
given above being those of the largest shell out of about 20 in the
two lots seen. A very similar small form was taken with O. haydeni
in the Wasatch Mountains many years ago by the Wheeler Expedition, but I think it will prove to be distinct. Its exact location in
that range is not known, and it was not among the forms taken by Hemphill there.
