MAMMALIA. 

 The principal dimensions of the above animals are as follows : — 



33 



Specimen from 



Buenos Ayres Maldonado. Valparaiso. 

 In. Lines. In. Lines. In. Lines. 



Length from nose to root of tail .99 93 86 



of tail Imperfect 6 6 6 



of tarsus 17 17 17 



East Falkland. East Falkland. Keeling Island. 

 In. Lines. In. Lines. In. Lines. 



8 9 9 8 3 



Imperfect 6 6 6 



17 17 17 



Upon comparing the skull of the Valparaiso variety with that of a British 

 specimen of Mus decumanus, I could perceive no difference. A skull from West 

 Falkland did not differ, neither did the dentition of the Keeling Island specimen 

 above noticed. A perfect specimen of this last I have not had an opportunity of 



examining:. 



2. Mus (decumanus var. 1) maurus. 



Mus maurus, Waterh. in Proceedings of the Zoological Society of London, for February, 1837, p. 20. 



31. pilis supra purpurescenti-nigris ; subtiis plumbeis ; auribus parvulis, pallide fuscis : 

 caudd corpus fere ceqaante. 



Description. — The character of the fur of this animal nearly resembles that of 

 Mus decumanus ; it is, however, of a harsher nature : the general colour of 

 the upper parts and sides of the body is purple-black, arising from the longest 

 hairs being of this colour, and likewise the tips of those which are next in 

 length ; the latter, however, excepting at the tip, are white, and this white 

 is not entirely hidden, even when the hairs are in their ordinary position : 

 on the head the hairs assume a brownish hue, and are tolerably uniform : the 

 limbs, and under parts of the body, are of a deep gray colour, with a faint 

 purple-brown wash : the under fur is gray : the ears are small, of a brown- 

 white, or very pale brown colour, and furnished with minute brown hairs : 

 the small, scattered, bristly hairs of the tail are of an uniform brownish-black 

 colour. The hairs of the moustaches are black at the base, and grayish at 

 the apex. 



Length from nose to root of tail 

 of tail 

 of tarsus 



In. Lines. 



11 3 



7 6 

 1 8 



Length of ear 



from nose to ear . 



In. Lines. 



o e± 



2 2 



Habitat, Maldonado, La Plata, (June.) 



