436 QUADRUMANES. 



the dentition is modified in analogical conformity with the 

 Rodent type, to which, in the present instance, it makes a very close 

 approximation, the canines being absent and a wide vacancy sepa- 

 rating the single pair of large curved scalpriform incisors in each 

 jaw from the short series of molars. (1) 



The upper incisors are compressed, presenting a narrow oval 

 transverse section, with the long diameter from before backwards ; 

 they are curved in the segment of a circle, and deeply implanted ; 

 the short exserted crowns touch one another ; their simple, widely 

 excavated fangs diverging as they penetrate the substance of the 

 jaw. The short crowns project obliquely forwards and do not 

 extend vertically downwards as in the true Rodentia. 



The lower incisors are more compressed, and of greater 

 breadth from before backwards, than the upper ones ; they are 

 more curved than in the Rodentia, describing a semicircle, two 

 thirds of which are lodged in the socket, which extends back- 

 wards beyond the last molar tooth to the base of the coronoid. 

 The anterior edge of the oblique cutting surface does not rest 

 against a posterior ridge of the surface of the tooth above, 

 whence M. de Blainville infers that these large scalpriform 

 teeth were put to a different use from that to which the same 

 teeth of the Rodents are habitually applied. He conjectures, 

 that they served the Cheiromys rather as a pair of cutting 

 pincers to remove the bark and perhaps the w^ood of trees in 

 search of larvae or insects, which, however, the smooth, flat 

 crowns of the molars would not indicate to have been the staple 

 food of the Cheiromys. The most important character by which 

 the incisors of this anomalous Lemur differ from those of the 

 Rodentia is the entire investment of enamel, which is, how- 

 ever, thicker upon the front than upon the back part of the 

 tooth. 



The molar teeth are four on each side of the upper jaw, 



(1) PI. 114, fig, 2. M. de Blainville, who first pointed out the afllnity of the Cheiromys 

 to the Quadrumana, has made the observation that the edentulous margin of the jaw between 

 the incisors and molars is sharp, as if it had lodged some syiall teeth that had been shed ; 

 whilst in the true Rodentia it is always broadly rounded off and smooth. 



