fc z .h l^ s h . e* d . AÆ drT 'ciÿ? J a ^ r& a jry T 8Z& .
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Ptekomys Sabrinus. var. (3. alpinus. Rocky Mountain
Flying-Squirrel.
Pteromys alpinus; R ic h a r d s o n , Zool.Joum. No. 12. p. 519. March, 1828.
Specimens û n t h e Z o o l o g ic a l M u s e u m a n d H u d s o n B a y C o .’s M u s .
Pteromys {alpinus), super, luteo-fuscus, caudt plant fulignet corpus longitudine excedenti, margine membranes volitantis
recto..
Rocky-Mountain.Flying-Squirrel, yellowish-brown above ; tail.flat, longer than the body, blackish-gray ; flying membrane
with a straight .border.
P l a t e x v i i i .
This animal was discovered by Mr. Drummond, on the Rocky Mountains, living
in dense pine-forests, and seldom venturing from its retreats, except in the night.
I have received specimens of it from the head of the Elk River, and also from the
south branch of the Mackenzie. It approaches nearer to the Pt. volans of Siberia
in the colour of its fur than to Pt. Sabrims, but it has.much resemblance, to
the latter in its form. It is entirely destitute of any rounded process of the flying
membrane behind the fore-leg*; and when its; scull is compared with that of
Pt. Sabrinus, the frontal bone between the orbits appears narrower. The size of
its limbs and tail is also greater. These remarks were made on a comparison
of the specimens of this animal, and of the Pt. Sabrinus, which I at first received,
and I was induced to think that they were specifically distinct; but having lately
had an opportunity of examining a more complete suite of specimens from
Hudson’s Bay, doubts were excited on the subject, and although it is probable,
from the distance between their respective localities, that they may prove eventually
to be distinct, I think it better at present to describe them as mere varieties.
Except that the size of both these species is considerably greater than that of Pt.
volans, they might be united with that species, without any great inconvenience.
D E S C R I P T IO N .
Dentition the same as in Pt. Sabrinus. Head and extremities larger than in the latter
animal \ and its tail is also longer, flatter, and has a more elliptical form. The flying-mem-
* In the accompanying plate the artist has fore-shortened the tail, so that it does not appear to possess its relative
length to the body, and the position he has given to the fore-foot has produced a slight rounding of the flying-membrane
at the elbow. The true form of the membrane is given in the figure in the distance.
2 C 2