Affinities of " Desmalopex " and Pteralopex. 217 



scapulatus and woodfoi'di, in wliich the teeth are not only 

 much shortened but excessively narrow, as in the Macro- 

 glossi. It would be hopeless to ''split " the genus Pteropus 

 on differences in the general outline of the cheek-teeth ; all 

 modifications lead through numerous transitional stages back 

 to the typical Pteropine molar. 



(9) '' Lower molars peculiar in that the ridges of mj and mg 

 are each divided into two low but distinct rounded cusps. 

 The quadritubercular form resulting from this is very 

 noticeable in mi, less so in vi\2." — I am probably not mis- 

 taken when I consider this to be, from Miller's point of 

 view, the chief character of his " Desmalopex." It will be 

 necessary, therefore, to make sure if Pt. leucopterus is not, 

 perhaps, in this respect as in all others very closely connected 

 with other species of the genus. In the type of " Pteropus 

 chinensis" (^== leucopterus) there is a shallow but distinct 

 transverse depression in the outer and inner ridge of mj, 

 indicating a beginning subdivision of each ridge into two 

 incompletely differentiated rounded tubercles ; the depres- 

 sion is still shallower in the outer than in the inner ridge ; 

 in m2 it is, in both ridges, exceedingly shallow, the 

 "quadritubercular'' structure of the tooth therefore only 

 detectable on very close examination. In the other skull of 

 Pteropus leucopterus (62.1. 14.3) I fail to discover the slightest 

 trace of a depression in the outer ridge of m^, while in the 

 inner ridge it is present, though less distinct than in the 

 other skull ; in nij a slight depression is present in the inner 

 ridge and barely detectable (at least with a lens) in the 

 outer ridge. It should be noted that in both skulls the 

 depression is more distinct in m^ than in m^, and more 

 distinct in the inner than in the outer ridge. In all the 

 skulls I have seen oi Pt. pselaphon (ten) the "splitting" of 

 the inner ridge of mj is either as distinct as or (in some 

 skulls) decidedly more distinct than in Pt. leucopterus , and 

 a similar, but much stronger, splitting of the inner ridge is 

 seen in p^ ; the inner ridge of m2 is simple, as are also the 

 outer ridges in all teeth. On close examination of a few 

 skulls of Pt. samuensis and one of Pt. pilosus I find a faint 

 depression in the inner ridge of p^, corresponding in position 

 to the deep groove in p4 of Pt. pselaphon. We have thus 

 these four progressive stages : a majority of species of 

 Pteropus, ridges of lower molariform teeth simple; Pt. 

 samuensis a.nd pilosus, a slight depression in inner ridge of p^, 

 suggesting an initial stage towards a splitting of the ridge 

 into two tubercles; Pt. pselaphon, inner ridges of p^ and m^ 

 very distinctly subdivided into an anterior and posterior 

 Ann, (k Mac. N. Hist. Ser. 8. Vol. iii. 15 



