151 



riod, or perhaps M. Cuvier may have described the dentition of 

 Phalangista Cookii and figured that of Petaurus Taguatioides. 



"Section 2. Belideus. — Dentition: Incisors, g; canines, g^ ; false 



molars, ^■, true molars, :^zZi^=^'^^- '^^^ anterior incisors of the 

 upper jaw are large, somewhat suddenly dilated immediately above 

 their insertion in the intermaxillaries, and assuming a triangular 

 form. In P. flaviventer they a.ve broader than in either P. sciureus or 

 the new species here described under the specific name of breviceps, 

 where these incisors are proportionately shorter, and perhaps a little 

 broader than in P. sciureus. The next incisor on each side is smaller 

 than the posterior one, narrow at the base, and broad at the apex. 

 The third incisor is broad, and has a sharp incurved cutting edge. 

 The canine is tolerably large, and has its origin close behind the in- 

 termaxillary suture ; in fact, is in the usual situation of the canine. 

 It is separated by a small space on either side from the false molars 

 and the incisors, compressed and pointed, and its anterior and posterior 

 edges are sharp. The apex projects beyond the level of either of 

 the molars. The first false molar on each side is rather large, broad, 

 compressed and pointed, has a very faint indication of an anterior 

 and posterior lobe, and two distinct fangs (which is not the case in 

 the small and cylindrical corresponding tooth in Petaurus Tagua- 

 noides). The second false molar is small, short, and compressed, 

 and has a minute anterior lobe. This tooth is separated by a con- 

 siderable space from the first false molar, and by a narrow space from 

 the third. The latter touches the first true molar, is narrow in 

 front, and consists chiefly of one triangular and pointed tubercle. 

 The first true molar on each side is considerably larger than the fol- 

 lowing molars, each of which is smaller than the preceding, so that 

 the last is not equal in bulk to one half of the first. With the ex- 

 ception of the last, all the true molars possess four somewhat blunt 

 and rounded tubercles, and in general appearance very much resem- 

 ble the corresponding teeth of a Squirrel. The last molar has but 

 three tubercles, two in front and one behind. 



" The incisors of the lower jaw are long, compressed, and pointed, 

 and have the upper and lower edges sharp ; they are almost horizon- 

 tal in their direction, being but slightly curved upwards. Next 

 follows a series of four small teeth on each side, which I have called 

 false molars, though possibly the last only is properly so called, that 

 having two fangs, whereas the others appear to have but one. The 

 true molars nearly resemble those of the upper jaw, though they 

 are narrower and longer. The first has a large irregular anterior 

 lobe, which is higher than the posterior portion of the tooth, which 

 is divided into two tubercles. The three posterior molars have each 

 four tubercles. 



" Besides the points of distinction already alluded to between the 

 species of the present section and the preceding, there are other 

 characters which cannot be considered unimportant. The space 

 occupied by the grinding teeth of the upper jaw, compared with the 

 space between the last incisor and the first true molar in the species of 



