XXU PLASTIC CHARACTERS. 



Nerviis and Vasa supraorhitalia). The oulj section of genera 

 in which exceptions to this rule occur is the Cynopterus section ; 

 the postorbital foramina are, within that group of Fruit-bats, 

 normall}" developed only in Myonycteris, Cynopterus, Ptenochirus, 

 and Aleycerops, minute (tending to disappear) in Dyacopterus, 

 generally absent (or, it' present, minute or traceable only on one 

 side of the skull) in Nyctiinene, always absent in Balionycteris, 

 Chironax, Thoopterus, Penthetor, and Sphcerias. 



5. Palate. 



Pteropus (fig. 6, p. 62) is probably one of the genera that shows 

 the Megachiropteran palate in its least modified form. The inter- 

 dental palate is only moderately broad, gradually narrowing in 

 front (the tooth-rows distinctly converging anteriorly); the post- 

 dental palate about one-fourth of the total length of the palate, its 

 lateral mai-gius forming almost straight lines converging posteriori)-. 

 In Ho usetius and Boneia the interdental palate is relatively broader; 

 an even greater increase of breadth is seen in Epomops, and in 

 Plerotes this portion of the palate reaches its maximum of breadth 

 (bearing a curious resemblance, in general outline, to that of the 

 Carnivorous genus Proteles !). An opposite course of development 

 is taken by Epomophorus, in which the palate is unusually narrow. 

 If the lower canines are slanted outward, this necessitates a greater 

 breadth of the palate anteriorly, between the upper canines, and 

 therefore more nearly parallel tooth-rows (ex. Boneia, Uypsi- 

 gnatJius, Macroglossus). 



The postdental palate is in the majority of genera essentially 

 similar to that of Pteropus described above ; it may be broader or 

 narrower, shorter or longer, more rapidly narrowing posteriorly 

 or more nearly parallel-margined ; in Nyctiraene it is somewhat 

 pandurate in outline, i. e. distinctly constricted at middle (owing 

 to the unusually broad mesopterygoid fossa ; compare the presence 

 of nasal tubes in this genus)- But these variations are com- 

 paratively trivial as compared with the modifications exhibited by 

 some genera of the Epomophorus section : — In Plerotes, Epomops, 

 Hypsigiiathus, and Scotonycteris it is relatively simple in shape, 

 though in the two former genera rather broader than usual ; but 

 in Epomopliorxis (fig. 36, p. 515) it is deeply depressed posteriorly, 

 and its posterior free margin high and prominent ; m Micro pteropus 

 (tig. 38, p. 555) it is abruptly narrowed behind the roots of the 

 zygomatic processes, the posterior depression is shallower, the free 

 margin prominent ; in Nanonycteris (fig. 40, p. 560) it is short, 

 but unusually broad, longitudinally depressed on either side, 

 slightly convex between, and flattened at the extreme posterior 

 extremity, the free edge not prominent ; and, finally, in Casinycteris 

 (fig. 43, p. 569), a genus in other respects closely similar to Scoto- 

 nycteris, the postdental palate has practically disappeared, the 

 mesopterygoid fossa extending forward very nearly to the level of 

 the posterior molar, a modification unique in Megachiroptera and 

 more closely recalling the type of palate found in Microchiroptera, 



