THE FAMILIES AND GENERA OF BATS. 59 



In extent of distribution and in the number of its species Pteropus 

 exceeds all other genera of Megachiroptera. It also has the most 

 complete and least modified dentition. These two circumstances have 

 caused the gerilis to be generally regarded as the most primitive of 

 the group; but it seems probable that the deflection and tubularity 

 of the brain case, the great reduction of the audital bullae, and the 

 complete absence of the tail are of more importance than the large 

 number of teeth, and that Pteropus is in reality less primitive than 

 Cynopterus, Rousettus, and Pterocyon. 



Genus ACERODON Jourdan. 



1837. Acerodon Joubdan, Ann. Sci. Nat., Paris, 2" ser., VIII, Zool., p. 369 

 (jubatus). 



1878. Pteropus Dobson, Catal. Chiropt. Brit. Mus., p. 15 (part). 



1899. Acerodon Matschie, Plederm. des Berliner Mus. fiir Naturk., p. 9 (sub- 

 genus of Pteropus. 



Type-species. — Pteropus -jubatus Eschscholtz. 



Geographic distribution. — Eastern part of the Malayan region 

 (Philippines, Djilolo, Batjan, Celebes, Flores, Timor, Sumba). 



Number of forms. — Seven or eight forms of Acerodon have been 

 described. 



Characters. — Like Pteropus, but with smaller canines and larger, 

 more complex molariform teeth. Dental formula as in Pteropus. 

 Upper incisors as in Pteropus, but somewhat more elongate and less 

 bluntly pointed. Lower incisors differing from those of Pteropus in 

 the much greater contrast in size between the inner and outer tooth 

 of each pair. Canines much shortened as compared with Pteropus, 

 the mandibular canine little exceeding the height of pm 3 . Though 

 reduced in length the canines retain their thickness, and the cingulum 

 is even better developed than in the related genus. Small premolars 

 as in Pteropus. Upper molariform teeth differing from those of 

 Pteropus in relatively greater size, greater breadth of crowns, greater 

 distinctness of cusps, and a peculiar trenchant character of the edges 

 and ridges. First large lower premolar {pm 3 ) essentially as in 

 Pteropus. The three succeeding teeth differ from those of all other 

 Pteropidas in the presence of a broad, flat postero-internal heel, 

 sharply differentiated from the two ridges and extending considerably 

 beyond them, especially behind. Cranial and external characters as 

 in Pteropus. 



Species examined. — Acerodon jubatus (Eschscholtz) and several 

 undetermined forms. 



Remarks. — Although not generally recognized as distinct from 

 Pteropus this genus is well characterized by the form of the lower 

 cheek teeth. Additional characters are furnished by the reduced size 

 of the canines and of the inner lower incisors. 



