151 



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

 Phalangista Cookii and figured that of Petaurus Taguanoides. 



" Section 2. Belideits. — Dentition: Incisors, -^•, canines, ^ ; falše 

 raolars, ^— ; true moiars, į::į=40. The anterior incisors of the 

 upper jaw are large, soraewhat suddenly dilated immediately above 

 their insertion ia the intermaxillaries, and assuming a triangular 

 form. In P . Jlaviventer thej aie broader than in eitherP. sc'mreus 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- 

 termaxillarj'^ suture ; in fact, is in the usual situation of the canine. 

 It is separated by a small space on either side from the falše moiars 

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

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

 the moiars. The first falše 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 smaU and cyUndrical con-esponding tooth in Petaurus Tagua- 

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

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

 siderable space from the first falše 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 considerablj"- larger than the fol- 

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

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

 ception of the lašt, all the true moiars possess four somewhat blunt 

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

 ble the corresponding teeth of a Sąuirrel. The lašt molar has but 

 three tubercles, t«o 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- 

 tai in their direction, being but slightly cur\-ed u])wards. Next 

 follows a series of four small teeth on each side, w'hich I have called 

 falše moiars, though possibly the lašt only is properly so called, that 

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

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

 are narrower and longer. Tlie first has a large in-egular anterior 

 lobe, •nhich is higher than the posterior portion of the tooth, ■nhich 

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

 four tubercles. 



" Besides the points of distinction already alluded to betvveen the 

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

 characters ^\hich cannot be considered unimportant. The space 

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

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



