326 Mr. 0. Thomas on a new Species o/'Loncheres. 



XLI. — On a new Species of luoncheres from British 

 Guiana. By Oldfield Thomas. 



I AM indebted to my friend and former colleague Mr. J. J. 

 Quelchj Director of the British-Guiana Museum, Demerara, 

 for the opportunity of examining a small collection of Mam- 

 malia from that country, and among them I find two speci- 

 mens of the following new species of spiny rat. 



Loncheres guiance, sp. n. 



Fur thickly spinous, the hairs between the spines scarcely 

 perceptible. Muzzle rich rufous ; crown of the head, fore 

 back, flanks, and outer sides of limbs coarsely grizzled black 

 and pale yellow, both hairs and spines slaty grey for four 

 fifths their length, the former with a subterminal band of pale 

 yellow, the latter black-tipped. Spines on posterior back 

 with a narrow orange tip, which gradually broadens and 

 deepens in colour until the rump is a bright rufous. Whis- 

 kers long and numerous, black. Chin, chest, belly, and inner 

 sides of limbs pale buff, the line of demarcation from the 

 colour of the sides fairly well defined. Tail murine in cha- 

 racter, thinly haired and scaly throughout, the scales large, 

 averaging about eight or nine to the centimetre ; the thinly 

 scattered hairs brown above, yellowish beneath. 



Measurements of an adult skin : — 



Head and body (c.) 190 millim. ; tail 167 ; hind foot 36-2 ; 

 ear (contracted) d'd. 



Skull, basal length (c.) 47, greatest breadth 26 ; nasals, 

 length 15'5, interorbital breadth 13; diastema 11*8; length 

 of upper molar series 11*2. 



This species is readily distinguishable by its peculiar colora- 

 tion from all the known species of Loncheres with one excep- 

 tion. This is "Isothrix^^ pagurus, Wagn.*, from Borba, 

 Brazil, which has much the same coloration, but differs from 

 L. guianoi by having wholly soft fur. That this absence of 

 spines in L. pagurus is not due to youth is shown not only by 

 the fact that the type specimen is slightly larger than that 

 of L. guianoi^ but also by the marked spininess of Mr. Quelch's 

 second specimen, which is only about two-thirds grown. 

 Nor is the difference a seasonal one, since the type of L. pa- 

 gurus was captured in July and the smaller Demeraran speci- 

 men in June. The larger specimen is unfortunately not 

 dated. 



* Arcli. f. Nat. 1845, p. 146 j Abh, Ak. Miiiicli v. p. 288 (1847). 



