PTEROMYS GENIBARBIS. 



constitutes a fascicle of long slender bristles, partially concealed by the second series, 

 spreading far from the head, and exhibiting a character very different from the brush- 

 like appendages which constitute the bearded or pencilUke auricles, in several 

 species of the genus Sciurus of Linnasus. A less perceptible tuft of long, delicate 

 hair arises hkewase from the anterior portion of the lobe of the ear. 



The eyes have the usual character both of those of the genus Pteromys and of 

 Sciurus ; they are large and prominent. The structure of the ear of our animal 

 presents several peculiarities, which distinguish it from the other Javanese species. 

 The interior of this organ is large, naked, and disposed transversely near the extre- 

 mity of the head ; it is divided, in the middle, by a continuation of the concha, 

 which separates an extensive meatus auditorius externus from the superior cavity. 

 The lobe is short, linear-oblong, with an inflected margin, and surrounds only the 

 superior portion of the ear ; opposite to the continuation of the concha, it descends 

 abruptly ; and from the base of its inflected margin, arises a thick tuft of silky 

 hair of a white colour. The naked interior portion is partially covered by the 

 bristles of the cheeks ; and the long hairs which arise from the anterior and posterior 

 portions of the lobe, have already been described as affording a peculiar character to 

 our animal. 



The teeth agree, in number and disposition, precisely with those of the other 

 species of Pteromys. The fh-st grinder in the upper jaw is very minute, and closely 

 applied to the second : the surfaces are generally uniform ; and being calculated for 

 trituration, present a few rounded tubercles. The crown of each, individually, has 

 an oblong form: they are arranged transversely, but in contact with each other, so 

 as to constitute an uniform, longitudinal, triturating ridge. The front teeth in the 

 upper jaw have the character which is given in the generic description of those in 

 the lower jaw ; the base only is remaining in our specimen. 



The proportion of the extremities to the body appears the same in all species 

 of Pteromys ; but in the flying -membrane, a slight pecuHarity is observed in this, 

 and in other Javanese species : the length of the cartilage which supports it anteriorly, 

 affords the capacity of forming a more complete expansion than in other species. 

 M. Cuvier observes, that both in the Pteromys Petaurista, and the Pt. Sagitta, the 

 membrane forms a very acute, salient angle behind the wrist : in the former, and in 

 a new species, above mentioned, the degree of expansion which this arrangement 

 affords, appears very evident: the attitude in which the Pteromys genibarbis was 

 placed, in the Museum, and which has been carefully preserved in the figure by the 

 artist, does not exlribit the membrane completely expanded. 



