514 Mr. K. Andersen on 



Rousettus is more primitive than Pterocyon ; but it is on a 

 higher level in the rather shorter rostrum, and the more 

 reduced p"^. The range of the genus Rousettus over the whole 

 of the Ethiopian and Oriental regions, the close affinity 

 of R. arahicus to the S. African R. Leachi^ the absence 

 of any representative of the genus from the whole of the 

 Mediterranean subregion except Egypt, are evidence that 

 its origin dates back to a time when, owing to different 

 physiographic conditions, Africa and S. Asia were much 

 more intimately connected than now. Pterocyon is a more 

 specialized Ethiopian offshoot of the common prototype. 



In its essential cranial and dental characters Myonycteris 

 is intermediate between Rousettus and Cynopterus, though 

 nearer to Cynojjterus. In Rousettus the basicranial axis is 

 very distinctly deflected J in Myonycteris^ as in Cynopterus^ 

 it is nearly parallel to the alveolar border. In Rousettus 

 the cranial rostrum has remained comparatively long, the 

 anterior edge of the orbital cavity being vertically above 

 the posterior half or middle of m} ; in Myonycteris the 

 rostrum is considerably shortened, chiefly owing to the 

 fact that the anterior edge of the orbital cavity is pressed 

 forward to a point vertically above the back of p*^ ; in 

 Cynopterus the rostrum is still shorter and stouter, the 

 anteorbital rim pressed still a little farther forward, to a 

 point above the middle of p^. From a glance at the dental 

 formula it would seem that Myonycteris (molars §) is closely 

 in accordance with Rousettus (f), and essentially different 

 from Cynopterus (^), but in reality Myonycteris is also in its 

 teeth nearer to Cynopterus ; in Rousettus w? is reduced in 

 size, in Myonycteris quite rudimentary, in Cynopterus lost; 

 in Rousettus mo is normal, m^, small ; in Myonycteris m^ is 

 much reduced in size, m^ rudimentary ; in Cynopterus m^ 

 much reduced in size, m^ lost. In short, the cranial and 

 dental peculiarities (non-deflection of brain-case, shortening 

 of rostrum, reduction of posterior molars) which distinguish 

 Jlfyonycteris from Rousettus have been preserved, or carried 

 still farther, in Cynopterus ; if the skull of Myonycteris were 

 known from a fossil state only, this bat would undoubtedly 

 have been declared a " connecting-link " between Rousettus 

 and Cynopterus. Also externally, in the form of the tip of the 

 muzzle (vertical furrow between nostrils deep and narrow, 

 inner margins of nostrils abruptly projecting), Myonycteris 

 closely approximates Cynopterus. 



The Species. — The three species of Pterocyon are closely 

 interrelated. Ft. Dupreanus, from Madagascar, with its 

 relatively longer rostrum and less modified fur-structure, is 



