PLASTIC CHARACTERS. XXVll 



halfway up the outer edge of the upper canine, in Fteralopex 

 (fig. 21, p. 483); a similar, strong cusp in Harjiyionycteris (fig. 78, 

 p. 800) ; often a more or less well-defined outer cusp in the upper 

 canine of jYyctimene (fig. 61, p. 684). 



From hoth edges : — A strong secondarj' (cingulum) cusp at lower 

 half of outer edge and a smaller one at middle of inner edge, in the 

 lower canine of Harpyionycteris (fig. 78, p. 800). In this genus, 

 it will be noticed, the upper canines are bicuspid, the lower 

 tricuspid. 



Grooves. — The anterior (or antero-medial) surface of the upper 

 canine is not infrequently marked with a deep and well-defined 

 longitudinnl groove, reaching nearly from the base to the tip of the 

 crown (and corresponding to the line followed by the tip of tho 

 lower canine, along the crown of the upper canine, when the lower 

 jaw is moved up and down) ; this groove is particularly con- 

 spicuous in Boneia (as a rule obsolescent or shallow in the related 

 liousettus), Pteropus (rarely obsolete ; in the related Pteralopex 

 shallower or rather indistinct), Styloctenhim, in all genera of the 

 Cynopterus section except Myonycteris, Cynopterus, Meyarops, and 

 Nyctimene, and in all Macroylossince. More rarely, and only in 

 some genera of Macroylossin(x, there are one or two additional 

 longitudinal grooves on the outer surface of the upper canine 

 (barely traceable in Macroglossus, shallow in Syconycteris, as a rule 

 better developed in Melonycteris, Nesonycteris, and 2iotopteris). 



Direction. — The lower canines are slanted conspicuously outward 

 or both outward and backward in Boneia, PleroU-s, Epomops, Eyp- 

 siynathus (lower canines, like lower incisors, closing some distance 

 in front of upper), Sphcerias, and all Maeroylossince. In Dolsonia 

 the upper canines are a little proclivous ; in the related Harpyio- 

 nycteris both upper and lower canines (as well as the incisors) are 

 unusually proclivous, the lower canines crossing the upper almost 

 at right angles. 



Position of lower canines. — In genera with a single pair of lower 

 incisors the lower canines have, as a rule, moved a little closer 

 together, toward the extremity of the jaw {Siyhctenium, Pteno- 

 cMrns, Meycprops, Balionycteris, Penthetor; not in the two Macro- 

 glossine genera Nesonycteris and Notopteris). The extreme phase 

 of this tendency is seen in three genera, Bohsonia, Harpyionycteris, 

 and Nijctimene, in which the lower canines have moved forward to 

 the very extremity of the jaw, so as to be quite or nearly in 

 contact with each other (in Dohsonia and Harpyionycteris the 

 single pair of lower incisors is rudimentary, wedged in between the 

 canines, and at least in Dohsonia sometimes deciduous ; in Nycti- 

 mene all lower incisors are lost). 



11. Premolars and molars. 



Formulct. — p^ and p^ are lost in all Chiroptera, m' in all Mega- 

 chiroptera ; no Fruit-bat, therefore, has more than ^ postcaniue 



