190
THE ESSEX NATURALIST.
introduction and establishment of a foreign mammal in a wild
state is a noteworthy event, and this is what has happened in
recent years, or is in the course of happening, with the American
grey squirrel; the present paper is an attempt to give some
account of this.
At the outset it may be remarked that although several of
the mammals included in the British list are not native and
came from foreign lands, namely, the rabbit, the fallow deer,
and both the black and the brown rat, yet some two hundred
years have passed since any species has succeeded in effecting a
secure foothold and residence. The brown rat was the latest
successful invader and it can be congratulated on certainly having
made good, for itself, if not for us.
Native Habitat—Name and Description.
In its native region the North American grey squirrel, Sciurus
carolinensis, Gmelin, has a wide distribution, ranging from
about 46o N in Lower Canada and New Brunswick to Northern
Florida and westward to the edge of the plains. Mr. R. I.
Pocock1 says that there are several local races, two of which
(a northern and a southern) are dominant, and that it is the
northern form that we have received as our guest in the British
Isles.
This is distinguished by the name Sciurus carolinensis leucotis,
but in the earlier period of its time with us it was called S.
cinereus. The latest authority has placed it in a separate genus
and named it Neosciurus carolinensis Gmelin2, but nomenclature
need not detain us here and we shall be satisfied with S. carolinen-
sis as a working name.
In external appearance the species differs very markedly
from the native British species, the common or red or light-
tailed squirrel, S. leucourus (Kerr), formerly called S. vulgaris
(the latter name now being confined to the species which inhabits
the Continent of Europe and a large part of northern and central
Asia). The grey squirrel is considerably larger than the red
squirrel, about 11 inches in length as compared with 9 inches
(in body), and in colour is uniformly greyish, grading from
darker shades on the upper parts to whitish underneath. The
1. The Field, 25th January, 1922, p. 135.
2. Hinton, History of British Mammals, Part 21, Octr., 1921, p. 718.