rTEKoi'is. 63 



Ciiniirps, ritfi(s, melanotus, niel(inoj)ogon (I'ostriun somewhat shorteucd 

 ill I't. Jcei/ensis), vampyrus^ alecto, i'onspicillatiix, and neohibernicus 

 groups. Leaving all minor differences out of consideration, the 

 prii]ci[)al aberrations from this general type may be classed under 

 the foHowing headings [(Jj) and (4)] : — 



(3) Modifications of skull in species with weak dentition (figs. 70, 

 8 C). — Species with small or excessively narrow premolars and molars 

 sho«- invariably all, or most of, the following modifications of the 

 skull : — Deflection of brain-case conspicuously greater than usual : 

 alveolar margin if projected backward passing through middle or 

 Tipper half, or even through upper margin, of sujiraoccipital ; coronoid 

 process of mnndiblc weak and much sloping; condyle of mandible 

 situated lower than usual, at level of or only slightly above alveolar 

 line ; temporal ridges more or less closely approximated, but not 

 fused to form a sagittal crest, or not fused throughout their whole 

 length ; brain-case much less constricted in front than usual, making 

 postorbital broader than interorbital constriction. Extremes of these 

 modifications of the skull are seen in Ft. scapalatus, tuoodfordi, and 

 jiersonatas (cheek-teeth excessively narrow), Pt. sidmlger, molosahms, 

 insrdaris, plueocephalas, temmiiicJci, epidarins, and mncrotl'i (teeth 

 smaller than usual). A similar adaptation of the skull is shown 

 by the extremely narrow-toothed liouseitus lanosus (fig. 3, p. 49) 

 compared with the normal-toothed species of llousettus (cf. also 

 ilacroglossime). 



Some species with weak dentition show no appreciable, or at least 

 no considerable, reduction of the length of the rostrum ; in these, the 

 teeth are iiormally spaced or may even be more spaced than usual 

 (Pt. scapidatu:^, tvoodfordi). Generally, however, weak dentition is 

 combined with a conspicuous shortening of the rostrum and conse- 

 quently rather more crowded arrangement of the teeth. In a few 

 species the shortening of the rostrum seems to be due chiefly to 

 eidargement of the orbits (Ft. temmincli, personcaus, e2ndarit's, 

 nuicrotis). 



(4) Short rostrum combined with heavy coronoid process (figs. 7B, 

 813). — In the typical Pteropine skull (as shown in figs. 6, 7 A, 

 and 8 A, 7'<. hypomelanus) the rostrum is rather long, the front of 

 the orbital cavity approximately vertically above the front of m', 

 the coronoid process moderately strong and somewhat sloping, tfie 

 coronoid height of the mandible less than the length of the lower 

 tooth-row, exclusive of incisors. In a small number of species, 

 viz. the typical forms of the Pt. pseJaphua group (Ft. pseJaphon 

 (fig. 8 B), 2n^06-i«s, tidiercidatus), all forms of the Pt. scunocnsiat type 

 ( Pt. nauaiensis, moioens-is, anetinnus, fig. 7B), and the typical iorma 

 of the Ft. lomhocens'is group (Pt. Jomhofcusis, 4-o/»7rov'»,s), these 

 characters are modified as follows : rostrum considerably shortened, 

 front of orbit above back, or posterior third, or even middle of \)\ 

 coronoid process uiiusually liigh, broad (aiitero-postcriorly), and 

 steeply ascending, coronoid height of mandible more than length of 

 lower tooth-row, exclusive of incisors. In all of these sj)ecip.s the 

 dcntitiim is heavier than usual, and in nearly all peculiarly modified 



