On Asiatic Baniboo-Ra(s. 311 



XXXVII. — Further Notes on Asiatic Bamboo-Rats. 

 By Oldfield Thomas. 



(Published bj permission of the Trustees of the British Museum.) 



SiNX'E writing my " Notes on the Asiatic Bamboo-Eats " * 

 I liave had, thanks to the kindness of Dr. Annandale, tlie 

 opi)ortunity of examining typical specimens of the species 

 described by BIyth as RJiizomys primiosus and castaneus, and 

 am therefore now able to make a further contribution to the 

 subject. 



Rhizomys prmnosuSf Blyth f. 



This species was described from Cherra Punji, Khasia 

 Hills, Assam, and specimens have since been referred to it 

 from various localities to the eastward as far as Yunnan. 

 Now, however, on comparison with the typical specimen 

 obtained by Mr. Skipwith at Cherra Punji, I find that the 

 more eastern specimens are distinguishable by their greater 

 size. The British Museum only contains young specimens 

 from the Khasia and Naga Hills ; but Mr. Skipwith's 

 specimen, fully adult, has a palatilar length of only 32'2 mm., 

 with length of upper molar series (crowns) 12 mm. ; breadth 

 of m^ 4"7. Compared with this the eastern form may be 

 described as follows : — 



Rhizomys senex, sp. n. 



As in R. pruinosu.'i, but size larger and teeth heavier. 



Colour and general appearance quite as in R. pruino.sus, 

 the fur similarly long, soft, slaty blackish, profusely grizzled 

 with the white tips to the longer hairs. Under surface paler 

 slaty varying towards greyish white. Hands and feet brown. 

 Mammte 1 — 3 = 8. 



Skull, as gauged by teeth, decidedly larger than in 

 R. pruiuosiis, but no perfect skull, fully adult, of the latter is 

 available. The zygomata are also decidedly broader (verti- 

 cally), the median height being in sene.v 9 mm., as compared 

 with 7*5 in pruinosus and 6'5 in sinensis. On the whole, the 

 skull is most like that of R. sinensis, but has a broader and 

 lower occipital plane, and, as indicated by its measurements 

 above, broader zygomata. 



* Ami. & Mag. Nat. Hist. (8) xvi. p. ."j6 (191.5). 

 t J. A. S. B. XX. p. 519(^1851). 



Ann. dD Mac/. N. Hist. Ser. 8. Vol. xvi. 22 



