I'LASTIC CnAEAClEES. 



In Pkropus i, is always conspicuouslj^ smaller than i„, and in 

 some species {I't. lomhocensis group) so luuch reduced as to be 

 almost rudimentary ; this foreshadows Stylodenium, in which ij is 

 completely lost, and Dobsonia and Ilui-pyionijcteris, in which both 

 ij and i' are lost. In those genera of the CynojJients section which 

 have the normal number of incisors i, is Aveaker than i„, and i" 

 iuintly shorter than i' ; this leads to those genera of the same 

 bcclion, viz. I'tenochirus, Meijcerops, Balionijcteris, and I'eniheior, in 

 which ij has disappeared and i" is shortened to about half the length 

 of i' ; and to JVyctimene (lower canines moved forward to extremity 

 of jaw), in which all lower incisors as well as i" have disappeared. 

 In the Macroglossine genus MeJonyctens \ is smaller than i.^, in the 

 closely related J^esomjcteris and Is'otoptivis it has disappeared. 



Differentiation. — In the majority of Fruit-bats the incisors are 

 small, thin, terete (styliform) or subterete, the crown only slightly 

 or even indistinctly differentiated from the shaft, the cutting-edge 

 of the lower incisors often faintly bilobed. Normally the incisors 

 above and below are placed approximately vertically, those in the 

 upper jaA\" in contact with each other or narroAvly spaced, but with 

 a relatively wide diastema on either side between the incisors and 

 canines, those in the lower jaAV crowded and in contact with the 

 canines. The principal variations, to be described below, from this 

 predominant type of incisors are, briefly summed up, these : (1) the 

 crown of some or all of the incisors may become peculiarly diifer- 

 entiated in shape, (2) conspicuous posterior ledges may be developed, 

 or (y) some of the incisors may be enlarged or reduced; further, 

 (4) the direction of the incisors may be altered, and (5) the spacing 

 of the incisors may be conspicuously unequal. 



In Fteroinis (and the closely allied Acerodon) the upper incisors 

 are larger than usual, the crown distinctly differentiated, posterior 

 basal ledges conspicuously developed, sometimes so much so as 

 to form a noticeable shelf (7^<. pscZo^^/ion group), i, always larger 

 than ij, either owing chiefly to a reduction of ij, which may 

 become nearly rudimentary (Pt. loinhocensis group), or chiefly to 

 an increase of i^ {Ft. samoensis and iisda^ihon groups). Some of 

 these tendencies are further developed in the related ger.us 

 I'teralopex : the posterior ledge of the upper incisors is very large, 

 shelf-like, rendering the antcro-posterior equal to or greater than 

 the transverse diameter of the teeth, and i, is from twelve to fifteen 

 times the bulk of i^, its cutting-edge unequally trifid (middle cusp 

 much the broadest). 



In Splurrias {Cynopterus section) both the upper and lower in- 

 cisors arc triangularly pointed. In Syconycteris {Macroijlossivcp) the 

 upper incisors are larger than usual, the crown well-differentiated, 

 narrowly chisel-shaped, i„ considerably higher and broader than i^, 

 with obliquely triangular crown. 



In those genera (Dolsonict, Ea)pyionyci^ri.i, ]\''yctimenc) which 

 have only [ — j or ^ — ^ incisors, and in which the lower canines are 

 situated close together or in actual contact at the anterior extremity 

 of the mandible, the single pair ol upper incisors is acted upon by 



