TEETH OF DIPHYODONTS. 311 



anticipated, in a remarkable degree from that of the insectivorous 

 kinds. The crushing instruments required for the food of the 

 latter are not needed ; and the true molars, 2 46 



with their bristled crowns, are entirely absent 

 in the Vampires (Desmodus), fig. 246. The 

 teeth, at the fore-part of the mouth, are espe- 

 cially developed, and fashioned for the inflic- 

 tion of a deep and clean triangular puncture, 

 like that made by a leech. The incisors are wwii and Teeth of the vam- 



•■ t , . -, i>ire-Bat (Desmodun Yum! 



two m number above, closely approximated, 

 one in each premaxillary bone, with a very large, compressed, 

 curved, and sharp-pointed crown, implanted by a strong fang which 

 extends into the maxillary bone. The upper canines have similar 

 large lancet-shaped crowns, and their bases touch those of the in- 

 cisors. In the lower jaw the incisors are two in number on each 

 side, much smaller than the upper pair, and with bilobed crowns. 

 The lower canines are nearly equal in size to those above, and 

 have similar piercing trenchant crowns. The molar series is reduced 

 above to two very small teeth, each with a simple compressed 

 conical crown, implanted by a single fang. The first two molars 

 below resemble those above ; but they are followed by a third, 

 which has a larger compressed and bilobed crown, implanted by 

 two fangs. This tooth corresponds with the last premolar in the 

 more normal genera. The dental formula of the true Desmodus 

 is thus reduced to — 



.1.1 1.1 2.2 _ 



The opposite extreme which the aberrant varieties of the Chei- 

 ropterous dentition attain is manifested in the great frugivorou 

 Bats : these constitute the genus Pteropus ; their dental formula 

 is — 



.2.2 1.1 2.2 3.3 

 i — ; c r-r-; p ; m — 34. 

 2.2 1.1 ' 3.3 3.3 



(vol. ii. p. 388, fig. 252) : their molars have broad flat crowns. 

 In some African Pteropi (Pt. macrocephalus and Pt. JVIutci) the 

 last small molar would seem to be wanting in both upper and 

 lower jaws. The deciduous teeth make their appearance above 

 the gum in Bats, as in Shrews, before birth ; but they attain a 

 more completely developed state, and are retained until a short 

 time after birth, when they are shed. 



The Colugos (Galeopithecus) resemble the Bats in the great 

 expanse of their parachute, formed by the fold of integument 

 extending on each side from the fore to the hind extremity, and 



