does not appear to have attracted the notice of naturalists. Pennant mentions a
yellow lateral line in his specimen which did not exist in the one Mr. Sabine
described, but this difference I attribute solely to the season in which they were
procured. Mr. Sabine’s specimen had its tail mutilated, an accident very common
to the whole family of rats. Pennant, under the name of Canada Jerboid rat, and
Colonel Davies, under that of Dipus Canadensis, describes another Jumping Mouse,
which sêems to differ from this in having ears shorter than the fur, but in
other respects to-be very similar to it. The Qerbillus Canadensis of Dr. Godman
agrees in description with Rafinesque-Smaltz’s Qerbillus soricinus, (D e sm a e e s t ,
Mamm., p. 332.) but has larger ears than the Canada rat of Pennant; and a
specimen in the Philadelphia Museum, described by Dr. Harlan, under the name
óf Qerbillus Canadensis, appears to be entirely similar to the Labrador species.
It is evident, therefore, that the Jumping Mice, inhabiting different districts of
America, require to be compared with each other before the true number of species
and their geographical distribution can be ascertained.
The Labrador Jumping Mouse is a very common animal in the fur countries as
far north as Great Slave Lake, and perhaps further, but I was not able to gain
any precise information respecting its habits,
D E S C R I P T IO N -.
Dental formula, incisors f, canines jjEö, grinders s=£ = 18.
Incisors of a deep orange colour. Upper ones short and strong, rounded anteriorly, each
marked near its exterior margin with a deep and conspicuous furrow, The lower ones are
longer and much more slender, but they taper very slightly towards their tips, and are not so
acute as the lower incisors of the genus mus. The grinders very much resemble in form those
of the squirrels. The anterior one in the upper jaw is round and very small. The other three
have slightly hollowed crowns, with points* as in the squirrels, on ptheir outward margins.
The second‘grinder has three of these points, and is also marked with a furrow on its inner
side. The third is very little larger than the second, and has Four points on the outer margin
of its crown, but no furrow on its inner side. The fourth is smaller than the two last-
mentioned ones, but considerably larger than the first one; it has two points on its
outer margin. In the lower jaw, the first and second grinders are nearly equal in size, and
the third or last is smaller. The zygomatic processes are scarcely arched, the breadth of the
scull being greater at their junction with the temporal bones than at their middles.
The head of this animal is narrow, and the nose, which is also narrow, but with a small
obtuse tip, projects about a line and a half beyond the incisors. The tip of the nose is covered
with short, erect hair, and beneath it the minute round openings of the nostrils face sideways,
and are protected anteriorly by a slight ventricose arching of their naked inner margins.
U