MAMMALIA. 



In. Lines. 



Length from nose to root of tail . .76 



of tail 7 6 



of tarsus . . . . . . 1 4r£ 



35 



In. Lines. 

 Lengtli of ear . • • • " ' 9 



from nose to ear . . • 1 ' 5 



Habitat, James Island, Galapagos Archipelago, Pacific Ocean, {October.) 



This species is scarcely equal in size to a full grown common black rat, {3Ius 

 Raitus), 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 31. 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 Mm 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. 



31. supra grisescenti, colore subtiis dilutiore; tarsis purpureo-nigris : caudd 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 



