INTERRELAXIONS OF GENEEA. 



liii 



{jalute, dental formula unmodified (except for the loss of i, and m^ 

 in ISti/lucteuinni), molar structure sometimes simple, but more often 

 sliowing some, though rarely {Pieralope.c) a high, degree of special- 

 ization, tail absent, and fifth metacarpal uearl}' always slightly 

 but distinctly longer than third and fourth ; and the Dobsonian 

 branch {Dohsonia, Harpy ionycteris) : rostrum at least somewhat 

 shortened, premaxillse reduced in breadth, lower canines situated 

 close together at the extremily of the mandible, i' and i^ lost, 

 molariform teeth with a pronounced tendency to a high degree of 

 specialization, tail present or absent, of the three long metacarpals 

 the third nearly always distinctly the longest, the fourth the 

 shortest, the tifih intermediate. The Kousettine branch (eighteen 

 species) has spread over the whole area inhabited by Megachiroptera, 

 except Polynesia; the Pteropine branch (ninetj'-four species, a 

 hundred and lifteen forms) covers the whole of the same area, 

 including Polynesia, bat excluding the continent of Africa and the 

 Eastern Medite:ranean countries ; while the Dobsonian branch 

 (thirteen species, fourteen forms) is confined to Austro-ilalaya and 

 the Philippines. 



The probable mutual affinities of the genera of the Rousettine 

 section are expressed in the diagram (fig. II.) on the foregoing page. 



The Epomophorine genus Plerotes (one species : Ethiopian) 

 probably originated from a primitive Uousettus-\\]\Q type. Except 

 lor the less of m'- its dental formula is typically Megachiropteran 

 (iu all other Epomophorine bats not only m", but also p' and m^ are 

 lost, and, as shown in fig. 28, p. 4S4, even in Plerotes these two 

 teeth are so small as to be nearly functionless), and its remarkably 

 simple palate-ridges are easily derived from those of Rousettus or 

 rather from a form in this respect somewhat more primitive than 

 the living representatives of that genus (see fig. 29, p. 485). But in 

 other respects Plerotes is highly specialized : the palate is unusually 

 broad, the cheek-teeth greatly reduced in breadth (almost Macro- 

 glossino), the molars and last premolar flattened, with scarcely a 

 trace of the usual cusp-like elevations, the lower canines slanted 

 outward, and the tail and calcar absent or rudimentary. 



Somewhat similar lines of development have been followed by 

 the related genus Epomops (three species, four forms : Ethiopian). 

 Like many, if not all, other Epomophori it subsists chiefly on soft 

 juicy fruits, the contents of which it draws out rather by suction 

 than by mastication, and its lips, pharynx, larynx, cranial rostrum, 

 dentition, and palate-ridges have been modified accordingly. The 

 lips are full, pendulous, and highly expansible; the pharynx long, 

 wide, and greatly extensible, communicating with the oral cavity 

 by a very restricted aperture, the larynx spacious, with ossified 

 walls, and supported behind by the expanded hyoids, acting as an 

 " exhauster" during the suction; the bony palate is broad (though 

 not broadened to the same extent as in Plerotes), the interdental 

 palate-ridges thick and prominent (fig. 31, p. 489), the canines and 



