500 On some South- American Muridse. 



naiTOWj its lateral ridges less strongly divergent than usual, 

 and running quite straight to the point on the parietals at 

 which they attain their greatest distance apart. Palatal 

 foramina slightly broader behind than in front. Posterior 

 palatal margin square, not V-shaped. 



Dimensions of the type (an adult male skin) : — 



Head and body 231 ; tail 207 ; hind foot (moistened) 48. 



Skull, see below. 



Hah. Believed to be Quito. The specimen came from 

 the collection of the late !Sir W. Jardine, for wliom a large 

 number of skins were collected at Quito by Mr. Jameson. 

 Sir W. Jardine also had a few specimens from Cayenne; but 

 as we have already seen that the Surinam Nectomys appears 

 referable to N. squamipes, tlie Quito locality is no doubt that 

 of the present very different animal. 



T?/pe. B.M. 86. 7. 2. 7. 



This species is readily distinguishable from all others by 

 its deep fulvous colour, which more resembles that of some of 

 the Couesi group of Oryzomys than that of the other members 

 of the present sombre-coloured group. 



Skull dimensions of Nectomys : — 



N. grandis. N.magdalena:. N.fulvinus. 



Basilar length 365 .... 



Lambda to nasal tip 42'2 39"7 41 



Greatest breadth 26 25 25 



Nasals, length 19-8 18-2 18 



„ breadth anteriorly . . 5-1 5 5'2 



„ greatest breadth be- 

 hind the constriction .... 4'2 3"7 4 



Interorbital breadth 7"2 7'8 7*1 



Greatest distance between 



temporal ridges 12-8 14-5 12-8 



Length of frontal suture ... . 15-1 13-9 14"8 



„ parietal suture . . 8-2 8-2 8-8 



Interparietal length 5-6 .... 



„ breadth 9 11-5 



Palate length from henseliou 22-4 208 21-8 



Diastema 13-2 125 13-2 



Palatine foramina, length . . 7"3 7*4 7-5 



„ „ breadth.. 31 34 32 



Length of upper molar series 7"6 71 7-1 



III. A peculiar Genus for " Oryzomys " instans. 



Further consideration has convinced me that the curious 

 little mouse I described * from Bogota under the provisional 

 name of Oryzomys instans should certainly be distinguished 



* Ann. Mag. Nat. Hist. (6) xvi. p. 368 (1895). 



