Pterocyon, Rousettus, and ^[yonycteris. 515 



apparently the least modified species. Pt. sabccus, from 

 S.W. Arabia, is a small-skulled and broad-toothed repre- 

 sentative of the African Pt. helvus. 



The eleven known species of Rousettus are referable to five 

 types : — (1) P. Leachi, cegyptiacus, and arahicus : rather 

 heavily built species, with strong rostrum and teeth, the 

 second phalanx of third digit lengthened, the pollex com- 

 paratively long ; distributed over Africa generally, Cyprus, 

 Palestine, Syria, and Arabia, as far east as Sind (Karachi) ; 

 P. a'gyptiacus is a larger-skulled modification of the R. Leachi 

 type ; P. arahicus is more closely related to the S. African 

 R. Leachi than to P. cegyptiacus. — (2) P. Leschenaultiy semt- 

 nudiis, amplexicaudatufi, mi7ior, and brachijotis : very closely 

 related to the species of the former group, but rather more 

 delicately built, with slenderer rostrum, feebler teeth, the 

 second }jhalanx of the third digit not lengthened, the pollex 

 comparatively shorter ; the members of this group are, pro- 

 bably, on the whole slightly less specialized than those of 

 the former ; P. Leschenaulti (continental S. Asia) and semi- 

 nudus (Ceylon) come near to the S. African R. Leachi in the 

 width of the interspace between c and p*, the size and shape 

 of w?3, the width of the ears, and the length of the tail ; in 

 the ludo-Malayan P. ample xicaudatus there is a tendency to 

 a reduction of the diastema c-p^, m^ is smaller and more 

 circular in outline, the ears narrower, the tail averaging 

 longer, the general dimensions smaller ; most of these 

 characters find a climax in the Austro-Malayan R. hrachyotis : 

 diastema c-// still more reduced, pr deciduous, ears still 

 smaller, size smaller. — (3) P. celehensis : peculiarly narrow 

 palate, narrow molars, longer and richer fur, small size, pro- 

 portionally long wings ; probably a modification of the 

 R. amplexicaudatus-hrachyotis type. — (4:) R. angolensis (Togo, 

 Cameroons, and Angola, to Ruwenzori), a peculiar species: 

 skull and teeth dift'ering in some details, fur long and 

 dense, coloration richer than usual. — (5) R. lanosus (Shoa, 

 Ruwenzori), the most aberrant species of the genus : molars 

 excessively narrow, fur very long and dense. 



From a more general point of view the first three of these 

 groups (the members of which are certainly more closely 

 related to each other than to those of groups -i and 5) may 

 be united into one section, giving a long chain of intimately 

 connected forms from W. Africa to the Solomon Islands ; 

 R. angolensis and still more P. lanosus are aberrant repre- 

 sentatives of this widely distributed type of bat. 



