1881.] MURID.E FROM CENI'RAL PERU. 457 



to that species. It should, however, be noted that there is in 

 the Museum collection a species, represented by three specimens, 

 agreeing externally quite as well as these with Mr. Tomes's descrip- 

 tion, but whose skull is wholly different, and proves it to belong to 

 the subgenus Oryzomys. To which of these two species therefore 

 the name caliginosw is really referable is a question which can only 

 be settled by an examination of Mr. Tomes's type. 



11. * Hesperomys (Habrothrix) xanthorhinus, Waterh. 

 a to c. Three specimens. Junin. 



Head m ■, „• ■, e . Forearm Ear- Muzzle 



t t_ i l;tu. lima toor. i i i i ., 



and body. and hand. conch. to ear. 



a. 6 76 57 17-8 22-6 105 20-0 



b. 6 75 57 177 21-8 1 15 20-5 



c. $ 73 57 177 21-3 120 194 



This is the most northern locality yet recorded for H. xantho- 

 rhinus, which has been hitherto only obtained from Chili and 

 Southern Patagonia. 



12. * Rheithrodon pictus, sp. n. (Plate XLIII. fig. 2.) 

 a to 1c. Eleven specimens. All from Junin. 



Head ™ .. Hind Forearm Ear- Muzzle 



and body. ' foot, and hand. conch. to ear. 



a. $ 121 91 25-1 34-0 214 29"9 



b. $ 109 89 24-1 29-7 195 28-5 



c. <3 109 88 24-3 31-0 18-3 280 



d. <3 108 91 26-6 33-0 18-3 26-6 



e. 6 108 90 24-9 31'6 188 27*8 



/. (J 107 90 25-4 29-9 20-4 26'6 



g. d 103 91 25-4 30 6 19-0 27"9 



h. J 102 82 25-3 29"4 19*3 25-4 



i. 6 (c)lOO 1 75 24-1 29-0 18-8 — 



Skull-dimensions. 



Total Basal Zygomatic Molar Inc. to 



length. length. breadth. series. m 1 . 



Off. d .... 28-0 26-5 17-0 5-6 7"1 



Palatal Palatal Interorbital Basal Lower 



length. foramen, constriction. axis. jaw. 



147 7-0 4-1 8-6 17*2 



Fur long, soft and silky, with very numerous longer black or grey 

 hairs intermixed. Upper side of head and neck clear grey, the 

 hairs slate-coloured for seven eighths of their length, then whitish, 

 with their extreme tips black. This grey gradually becomes darker 

 and more grizzled on the shoulders, while on the back the white of 

 the hairs gradually becomes more and more rufous until the rump is 



1 Skull out. 



