424 Mr. O. Thomas on 



short, blackish brown. Hands and feet very thinly haired, 

 flesh-coloured, the fine hairs whitish. Tail not as long as the 

 body without the head, almost naked, the scales very large 

 (about six rings to the cm.), uniformly pale brown. 

 Mammae 2 — 2 = 8, as in R. mordax, not 1 — 2 = 6, as in 

 R. leucopus *, ringens, and ratticolor. 



Skull about as large as in R. ratticolor. Zygomata well 

 thrown out anteriorly. Supraorbital beads well developed, 

 passing backwards to the middle of the parietals, but not 

 forming postorbital processes. Palatine foramina large and 

 well open, their hinder edge level with the front root of TO 1 . 

 Choanal opening broad, some way behind molars. Bullae of 

 medium size. Incisors somewhat opisthodont, index about 

 65°. Molars as usual. 



Dimensions of the type : — 



Head and body 210 mm.; tail 172; hind foot 45; 

 ear 22. 



Skull : greatest length 51 (in an older male 51'7) ; con- 

 dylo-incisive length 48 ; zygomatic breadth 24; nasals 20'5; 

 interorbital breadth 7*2 ; breadth of brain-case 19*5 ; palatilar 

 length 25'5 ; palatal foramina 9*5 ; breadth of choana3 4 , 6; 

 upper molar series 8*5. 



Ilab. as above. 



Type. Adult female. B.M. no. 20. 7. 26. 7. Original 

 number 29. Collected February 1920. 



This rat is easily distinguishable by its much greater size, 

 reddish colour, and white belly from M. mordax, which alone 

 of this group of Papuan species has its mammary formula. 



The name of Mr. Felix Pratt, one of the members of the 

 expedition, is remembered in the name given to this fine 

 species. 



5. Rattus monuselce, sp. n. 



S . 1, 2, 3, 15, 20 ; ? . 11, 19. Mt. Manusela. 4000'. 

 ? in formalin. 6000'. 

 " Trapped in heavy jungle." 



A mountain representative of the widely spread R. ru- 

 fescens group. 



* At a time when the genus Rattus was called Mus, Alston (P. Z. S. 

 1879, p. 646) rightly renamed Gray's Acanthomys leucopus, on the ground 

 that, being a member of " Mus," the specific name was preoccupied by 

 the American Mus leucopus, a species of Peroinyscus. 



But now that the genus bears the name Rattus — and, of course, the 

 Peromyscus never had that name applied to it — Gray's name should 

 apparently be reinstated, and the Queensland species long known as 

 41 Mus terra-regime, Alst.," be called Rattus leucopus, Gray. The female 

 specimen, no. 67. 5. 6. 4, may be selected as its lectotype. 



