Dr. W. Peters on Platacanthomys lasiurus. 213 



April 25, 1865.— Dr. J. E. Gray, F.R.S., in the Chair. 



Note on the Systematic Position of Platacanthomys 

 LASIURUS. By Dr. W. Peters, For. Memb. 



Amongst the many interesting objects which have come under my 

 observation in the British Museum through the kindness of my 

 friends Prof. Owen, Dr. Gray, and Dr. Giinther, is a specimen of the 

 curious Rodent shortly noticed by Mr. Blyth (Journ. A. S. B. xxviii. 

 p. 289) under the name oi Platacanthomys lasiurus. The specimen 

 in question is that exhibited by Mr. Sclater at a Meeting of this 

 Society in I860*, and subsequently presented by him to the British 

 Museum. 



It has always been difficult to me and other workers on the Mam- 

 mals to understand how a Rodent with only three molars in each 

 jaw could be referred to the Myoxina ; and I was therefore very 

 anxious to examine this very interesting form. But the results of my 

 observations will show that Platacanthomys does not belong to the 

 Dormice, but appertains strictly to the Murine family of Rodents, 

 being nearly allied in many respects to Phlceomys and Meriones. 



The generic characters of Platacanthomys may stand as follows : — 



Platacanthomys, Blyth. 

 Habitus myoxinus. Rostrum acutum, rhinario nudo, lahro fisso ; 

 oculi mediocres ; auricula mediocres nudce ; vellus molle, setis 

 dorsalibus latis sulcatis ; artus mediocres, palmce plantceque 

 pentadactylce, digito primo abbreviato, falculis modicis curva- 

 tis, acutis ; Cauda villosa, versus apicemfere disticha. Denies 

 primores leeves, compressi, acuti, molares utrinque y, complicati' 

 Cranium murinum, sed foraminibus incisivis parvis, coarctatis, 

 ossibus intermaxillaribus inclusis, palato perforato et processu 

 coronoideo brevissimo. Ossa antibrachii sejuncta, cruris con- 

 nata. 

 The resemblance of this genus to the Dormouse, at first sight, 

 is very striking, principally on account of the long-haired tail. But 

 in other respects, in its smaller eyes, very thin ears, and the well- 

 developed, although very short, thumb of the fore foot, it more ap- 

 proaches several Murine genera of Tropical India. 



The skull is rather broad and flattened behind ; but it is quite 

 impossible for any one who knows anything about the craniological 

 characters of the Rodentia not to recognize at first sight the typical 

 form of the Murince, in the two-rooted zygomatic process of the 

 upper jaw, together with the peculiar form of the foramen infra- 

 orbitale, which is very high, narrowed, and widened above, and in ' 

 the development of supra-orbital ridges, which form together a lyri- 

 form figure. As peculiar and deviating from the typical skull of 

 the Murince, are before all to be noted the small and narrow fora- 

 mina incisiva formed only by the intermaxillary bones, the imper- 

 fect perforate palate, and the very short coronoid process of the 

 lower jaw. 



* See P. Z. S. 1860, p. 260. 



