EHIZOMYS. 323 



long ago as 1841, pointed out that the drawing of Mtts sumatrensis had not been 

 deposited with the Calcutta Society, but with the Eoyal Asiatic Society of London, 

 where it still remains, and where I have recently examined it. The specimen itself 

 has not been traced. 



Temminck considered that the term H. sumatrensis in being applied to the dehcm 

 was apt to mislead, as the typical specimen was from Malacca, and because the 

 species had not been found to exist in Sumatra. He therefore changed the specific 

 name, substituting the term dekan, the Malayan cognomen of the bamboo-rat; 

 and in this change he has been followed by Gervais, Schinz, Giebel, and A. M.- 

 Edwards. But if the principle which guided Temminck were to be universally 

 applied, it would only tend to burden the literature of these subjects with synonyms; 

 and I do not think that this instance is so important as to call for a change of name. 

 If there were any doubt regarding the identity of the form described by Eaffles as 

 Mus stimatrensis, and that described by Temminck as Nyctocleptes dekan, and aU 

 the records of the former were lost, the case would be different ; but as the 

 drawing of the former still exists, and is Undoubtedly a representation of the dekan, 

 it seems to me that the first name applied to the species should meet with the 

 acceptance of zoologists. It must also be borne in mind that Eaffies himself stated 

 distinctly that the animal was found at Malacca, where it was known to the natives 

 as dekan ; but this term when applied to the species is liable even to a more serious 

 objection than sumatrensis, because I have observed in an oflicial catalogue that it 

 has been construed and interpreted as indicating the habitat of the animal, assign- 

 ing it to the Deccan of Central India, a province zoologically very distinct from 

 Malay ana, of which Sumatra forms a part. The British Museum specimens of this 

 animal which I have examined leave no doubt as to their identity with the Mus 

 sumatrensis of Eaffles. 



This species attains to a much greater size than any of the others : Eaffles gives 

 the dimensions of his animal as 17 inches, exclusive of the tail which was 6 inches 

 long ; and there are larger examples in the India Museum, London, and having much 

 , the same characters as those indicated by Eaffles. In the young the head is 

 more or less rufous, and sometimes even bright red ; and the white spot on the vertex 

 between the eyes is always present, either lying in, or succeeded by, the dark-brown 

 band, which breaks up on the back into scattered brown hairs. The under parts 

 are concolorous with the sides. In the adult, however, the rufous of the head and 

 the white spot become fainter, and the brown band in some is either wholly lost 

 or broken up into straggling hairs. In connection with the coloration of the head 

 of the young, one is struck with its general resemblance to that of the nearly allied 

 form, Siphneus. 



The skull of JR. sumatrensis, Eaffles, is very large and massive, and distin- 

 guished from the other species of Rhizomys by the long, triangular, flattened and 

 expanded frontal area, and the flattened and almost vertical character of the inner 

 waU. of the zygomatic fossa, which is rounded in B. pruinosus, Blyth, and more so 

 in R. badius, Hodgson. The frontal contraction is also placed much posterior to 



