102 HYDROMYS. 



2. HYDROMYS FULVOLAVATUS, Gould (1863). 

 "Western Water Rat. 



General color of fur orange-buff or buffy-brown, but the 

 numerous black hairs which are dispersed over the upper surface 

 give those parts a dusky hue ; the whiskers, which in the other 

 species are entirely black, are in this mixed black and white , 

 outer surface of limbs dark brown ; upper surface of hind limbs 

 pale brown, deepening towards the toes ; nails white ; tail black, 

 except the extreme tip which is white. 



Habitat. South and West Australia. 



Reference. Gould, Mamm. Austr. iii. pis. xxv.(H.fulvolavatus) 

 and xxvii. (H. fuliyinosus). 



Note. As with its eastern representative there are two distinct 

 color varieties of the Western Water Rat. Mr. Oldfield Thomas 

 apparently considers ^v. Proc. Zool. Soc., 1889, p. 247) all six 

 described forms of Hydromys to belong to one and the same 

 species. His words are as follows : " One of the most singular, 

 and at the same time the most isolated genera of Mur-idcr, is 

 Uydromys, of which the only species is the well-known Australian 

 Water-rat." According to this H. chrysogaster is the name by 

 which the sole species should be known. 



Genus II. XEROMYS, Thomas (1889). 



External form murine. Tip of muzzle as in Mus, not as in 

 Hydromys. Toes unwebbed. Tail scaly, very finely haired. 

 Skull as in Mus, except that the supraorbital edges are rounded, 

 teeth both in number and structure as in Hydromys. Infra- 

 orbital foramen typically murine, the outer wall broad and 

 slightly projecting forwards. 



Distribution. Queensland. 

 Dentition. I. j, M. \ = 12. 

 Habits. Terrestrial. 



1. XEROMYS MYOIDES, Thomas (1889). 

 Thomas' Bat. 







External appearance like that of an ordinary Rat. Ears short 

 and rounded, laid forward they only reach to within three or 

 four millimetres of the posterior canthus of the eye ; their 

 anterior edge without the supplementary Hap found in Hydromys. 

 Fur very short, uniform in length. Whiskers as in Mus, fewer 

 and slenderer than in Hydromys. General color above dark 

 slaty-gray, below white. Ears gray. Arms and legs like the 

 back ; hands and feet very thinly haired, almost naked terminally, 



