692 NTCTIMENE. 



canines;; these, again, have directly or indirectly necessitated a 

 series of other modifications of the skull and dentition. The 

 characters of tho present genus may therefore conveniently he 

 discussed under the following three headings, viz., those (certainly 

 or prohablj') dependent on the development of nasal tubes, those 

 relating to tho dentition, and those acquired apparently indepen- 

 dently of both. 



(1) The nasal tubes. — What purpose the peculiar cylindrical 

 nasal tubes serve in the life-history of these animals is so far 

 entirely unknown ; but they represent, in fact, scarcely more than 

 an excessive development of a tendency traceable in most other 

 Fruit-bats; iti nearly all genera the nostrils project a little from 

 the surface of the muzzle, in the Cynopterine group, in general, so 

 conspicuously so that they may properly be described as sub- 

 tubular, and in Megcerops the character is still a little more 

 emphasized than in its nearest relatives. The nasal tubes in 

 Nyctlmene have effected some modifications of the bones forming 

 the upper, lower, and lateral margins of the anterior nares : — the 

 median portion of the nasals is produced forward and downward as 

 a triangular projection firmly united with the front edge of the 

 mesethraoid cartilage and evidently acting as a support of the 

 tubes ; for the same purpose the upper margin of the alveolar 

 branches of the premaxilte is expanded upward (as a rule also 

 slightly forward), this strengthening and expansion of the pre- 

 maxillae accounting both for the great vertical depth of these bones 

 and for the very early disappearance of the inter-premaxillary 

 suture, perhaps, in some measure, also for the unusually great 

 depth of the rostrum as a whole ; at the same time the nasal 

 branches of the premaxillae (very thin in Cynopterine bats) have 

 been so much shortened as to lose their contact with the nasal 

 bones. Associated •with the strong development of the nasal 

 tubes is a considerable widening of the posterior narial passage and 

 mesopter3'goid fossa, the latter being enlarged both in breadth and 

 depth. 



(2) The dental characters. — In Cynopterine bats the incisors, 

 above and below, are weak (as compared with those of Pteropus 

 and Roiisettus), and throughout the whole group there is a distinct 

 tendency of the lower canines to move closer together at the 

 extremity of the jaw ; even in those genera which have the full 

 Megachiropteran number of incisors, the inner lower pair (i^) is 

 conspicuously weaker than the outer, and in several genera it has 

 disappeared ; in the latter case the outer pair in the premaxillae 

 (i*) is always considerably reduced in size. These tendencies have 

 been further developed in Nyctimene : the lower canines have moved 

 forward to the extremity of the mandible, thus situated so close 

 together (generally in actual contact) as to leave no room at all for 

 lower incisors, which therefore have entirely disappeared, while at 

 the same time that pair of upper incisors (i''), which in some other 

 Cynopterine genera is on the point of degeneration, has also been 



