MAMMALIA. 
35 
Length from nose to root of tail 
of tail 
of tarsus . 
In. Lines. 
. 7 6 
. 7 6 
. 1 4 * 
Length of ear 
from nose to ear . 
In. Lines. 
0 7i 
1 7i 
Habitat, James Island, Galapagos Archipelago, Pacific Ocean, {October.) 
This species is scarcely equal in size to a full grown common black rat, {Mus 
Raltus), the head is rather shorter in proportion, the tarsi are smaller, and the 
tail is longer. In the character of the fur, and length of the hairs, it very closely 
resembles that species : the ears are larger than in M. decumanus, and about 
equal to those of M. Rattus. In having the hairs of the under parts of the body 
of an uniform colour, (i. e. not gray at the base,) it resembles the Mus Tectorum 
of Savi ; but the large size of that animal, the greater length of the fur, and its 
colouring, all serve to distinguish it from the present species, which I may here 
observe, is truly an old world form, and very distinct from another species, also 
from the Galapagos, which is hereafter described. 
“ It is very common in James Island, but is not found on all the islands, 
if on any other in the Archipelago. Although its appearance is so like that of 
the common rat, yet its habits appear to be rather different : it is less carni- 
vorous, and does not appear to be so strongly attached to the habitations of man. 
This island was frequented, about one hundred and fifty years since, by the ves- 
sels belonging to the Bucaniers ; so that the common rat might easily have been 
transported here. And if a very peculiar climate, a volcanic soil, and strange 
food, can together produce a race, or strongly marked variety, there is every 
probability of such change having taken place in this case.” — D. 
4. Mus (Rattus var.?) insularis. 
M. supra grisescenti, colore subtiis dilutiore; tar sis purpureo-nigris : cauda corpus 
cum capite cequante : auribus mediocribus : vellere molli. 
Description. — No. 1. The general colour of this animal is what might be termed 
black, there is, however, an obscure purple-brown hue on the upper parts of the 
body, and the sides and under parts have a grayish tint, the hairs covering 
the feet above are of an uniform deep purple-brown, almost black. All the 
hairs of the body are gray at the base : the hairs of the moustaches are long 
and numerous, and of a black colour, having one or two white hairs inter- 
mixed : the ears are of moderate size, and very sparingly furnished with 
f 2 
