218 Mr. K. Andersen on the Characters and 



portion; Pt. leucoptey^us , A.himci depression in inner ridges of 

 mi and m,, and, at least sometimes, in outer ridges ot same 

 teeth. "When to this it is added that Pt. pi/osus (Pelew 

 Islands), which in this respect marks an intermediate stage 

 between the typical Pteropine dentition and that of Pt. 

 pselaphon (Bonin Islands), is the closest known relative of 

 Pt. pselaphon, then the evidence seems to me conclusive. 

 This more or less incomplete, or, if preferred, more or less 

 complete, splitting of the longitudinal ridges of certain 

 cheek-teeth may be used as a specific character (though even 

 as such it is not of much practical use), but it is certainly 

 not of generic importance. 



Conclusions. — Pt. leucopterus accords with the typical * 

 species of the Pt. pselaphongroup [Pt. pselaphon, pilosus,taber- 

 culatus) in the following characters : — (1) The general shape of 

 the skull ; (2) the broad rostrum; (3) the strong supraorbital 

 processes ; (4) the heavy premaxillae ; (5) the large upper 

 incisors; (6) the unusually broad cingulum of the upper 

 incisors ; (7) the enlargement of \2 ; (8) the heavy canines, 

 ■with unusually broad cingulum, the edge of which shows a 

 pronounced tendency to split into separate rounded tubercles; 

 (9) the large pi ; (10) the heavy posterior basal ledges of 

 the molariform teeth above and below; (11) the tendency 

 to a splitting of the ridges of some of the lower cheek-teeth ; 



(12) the distribution of the fur (tibiae densely clothed above); 



(13) the size and form of the ears ; (14) the general size of 

 the animal. The only noteworthy peculiar characters of 

 Pt. leucopterus are, in fact, the shortening of the cheek-teeth 

 (in which respect it is, however, approached by Pt. insularis 

 aud phceocephaius, both allied to Pt. pselaphon) and 

 perhaps the paler colour of the fur (the three specimens 

 known are faded). In the face of this evidence I have 

 not the slightest hesitation in saying that Pt. leucopterus, 

 far from constituting a distinct genus, is simply a Philippine 

 representative of the Pt. pselaphon group. Pt. pselaphon 

 inhabits the Bonin Islands, Pt. pilosus the Pelew Islands, 

 the habitat of Pt. tuberculatus is unknown, but may, not 

 unlikely, be the Mariannes, so that also the geography is in 

 favour of this conclusion. 



The Affinities of Pteralopex. 



Desmalopex, Miller writes [t. c. p. 60), "is intermediate 



between Pteropus and Pteralopex, though nearer the former. 



In the broadened rostrum and slightly upturned orbits the 



skull distinctly suggests Pteralopex, while the same tendency 



* I consider Pt. insularis (Ruck atoll, Caroliues) and Pt. phesocephalus 

 (Mortlock, Carolines) somewhat aberrant members of the Pt. pselaphon 

 group. 



