MURIDE 465 
Fossil remains of Neotoma from cavern-deposits in Pennsylvania 
are not improbably referable to the existing Florida Rat (WV. 
flridana). Paciculus, from the Miocene of the United States, is 
regarded as an allied extinct genus with enamel-folds to the molars. 
Hypogeomys1—This and the following genera are confined 
to Madagascar, where they are the sole representatives of the 
Rodentia. Hypogeomys is a very peculiar form of large size, with 
long ears, feet, and tail. There is only one species, H. antimena, a 
fawn-coloured Rat about 9 inches long. 
Nesomys.2—Contains two species of long-haired Rats, more or 
less rufous in colour, about the size of the Brown Rat. 
Brachytarsomys.2—Represented only by B. albicauda, a pretty 
velvety-haired fawn-coloured Rat, with short feet and a long tail. 
Hallomys.t—The only species (H. audeberti) is very like a 
Nesomys, but has much longer hind feet. 
Eliurus.5—Represented by one small Dormouse-like species, 
characterised by its nearly naked and short ears, and long tail, of 
which the proximal third is scaly, and the remainder covered 
with long hair. The pollex is rudimental, but the hallux well 
developed. 
Subfamily Arvieolinze.—Molars usually imperfectly rooted or 
rootless, and composed of two longitudinal rows of triangular 
prisms placed alternately 
(Fig. 207). Tail moderate 
or short. Common to the 
Palearctic and Nearctic 
regions. 
The Voles, as the members 
of this group are commonly 
termed, are so closely con- 
nected with the Cricetines 
that they may be regarded 
merely as a branch of that 
subfamily which has attained 
a peculiarly specialised type 
ai Fic. 207.—Upper (A) and lower (B) molars of the 
of molar dentition. The Water-Vole (Arvicola amphibius). 
Voles are externally dis- 
tinguished, as a rule, from true Rats and Mice by their more 
clumsy and heavy build and less graceful movements ; by the small 
size of their eyes, the bluntness of the muzzle, the small ears, and 
the shorter limbs and tail. 
1 Grandidier, Rev. and Mag. Zool. 1869, p. 388. 
2 Peters, Sitzber. Ges. Nat. Freunde, 1870, p. 54 (1871). 
3 Giinther, Proc. Zool. Soc. 1875, p. 79. 
4 Jentink, Notes Leyd. Mus. vol. i. p. 107, note 27 (1879). 
5 Milne-Edwards, Ann. Sci. Nat. sér. 6, vol. xx. art. 1, bis, p. 1 (1886). 
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