FLYING-FOXES. 



101 



even on the flying membrane. The colour 

 of the fur is always dark, sometimes inclining 

 more to gray, sometimes to black, sometimes 

 to brown or fawn-colour, almost always uni- 

 form. Spotted or striped bats are very few 

 indeed. 



The number of genera is very large, above 

 60; that of the species which have been so 

 far distinguished, upwards of 3OO. 1 They are 

 distributed over the whole earth, wherever 

 there is a sufficiency of insects, even reaching 

 as far as the snowy regions round the poles 

 and high up in the mountains. The grouping 

 of the species in genera, and of genera in 

 families, is extremely difficult in consequence 

 of the varied nature of the dentition and the 

 frequently unimportant character of the other 

 differences; and on that account we have 

 confined ourselves principally to our native 

 European forms, taking into consideration 

 only a few very peculiar forms belonging to 

 more distant regions. 



First of all, the order may be divided into 

 two groups the Fruit-eating Bats (Carpo- 

 phaga or Frugivora) and the Insect-eating 

 Bats (Entomophaga). The former is not 

 numerous, being made up of the single family 

 of the flying -foxes (Pteropida). The other 

 group comprises all the rest. 



THE FRUIT-EATING BATS 



(CARPOPHAGA). 



Flying-foxes (Pteropida). 



With flattened masticating molars, and mostly with a clawed 

 second digit on the fore-limb ; snout long. 



Natives of the Old World, Australia, and 

 the South Sea Islands, these large bats, the 

 largest species of which, the kalong, spans 

 with outstretched wings a width of five feet, 

 are mainly distinguished by their dentition, 

 partly also by the structure of their wings; 

 but with these distinctions are associated 



1 Mr. G. E. Dobson in his treatise on the Chiroptera describes 

 400 species distributed among 80 genera. 



many other anatomical and embryological 

 peculiarities. 



The skull is long, the brain -case pear- 

 shaped, separated from the facial region by a 

 marked constriction, the orbits scarcely sepa- 

 rated from the temporal fossae or depressions 

 at the temples, the snout projecting, the nose 

 formed in the usual manner. The premaxilla 

 is well developed, closed in the form of a bow 

 under the cavity of the nose, and carries two 

 small vertically placed incisors. There then 

 follows a large sharp mostly recurved canine, 

 which is immediately succeeded by a very 

 small recurved premolar, which, however, 

 frequently drops out or remains undeveloped. 

 There next comes an interval without teeth, 

 and then three molars, which decrease in size 

 from before backwards; and finally a small 

 tubercled tooth placed somewhat to the inside 

 out of the series. In the lower jaw incisors 

 and canines are similar, the premolar some- 

 what larger, and instead of three there are 

 four molars, and behind these again the small 

 tubercled tooth. The dental formula is thus 



= ?A. The form of the molars is 

 2 i i 5 



extremely peculiar in both jaws. In the 

 young animal they consist of two lateral 

 triangular plates of enamel, which meet to- 

 gether, and are elevated at the middle and at 

 both ends of the tooth. The enamel plates 

 are separated from each other by a deep 

 groove, and the teeth so formed present a 

 distant resemblance to the molars of many 

 ruminants. Seen from the side, these teeth 

 appear to have only one triangular cusp, for 

 the outer cusp is higher than the inner. In 

 the adult animal the crowns of the teeth get 

 so worn away that they exhibit a rounded 

 grinding surface sloping down inwards. It 

 is thus not an original pure insectivorous 

 dentition which the flying-foxes possess; the 

 sharp canines and molar cusps contradict that ; 

 but it becomes converted into a dentition of 

 that kind by use, and accordingly it may be 

 surmised that the young flying-foxes feed on 



