118 MR. K. ANDERSE>f ON BATS [May 16, 



the African coast of the Gulf of Aden. It is the closest existing 

 relative of the Hionalayan Rh. afjinis : the same shape of the 

 skull ; the same shape of the sella, of the connecting process, of 

 the ears ; the same structure of the wings (also the same lengthening 

 of III.") ; the same proportionate length of the tail. But it is 

 more advanced in dentition : p., is not only external (as in affinis), 

 but very often lost ; p", which in affinis is still in the tooth-row, 

 is in clivos'us external and veiy small. In shoi't : lih. clivosus is 

 a "jff/i. affinis" with. ferrum-equinum dentition. 



The clivosits type has found its way very far into the Ethio- 

 pian Region. Rh. darlhigi *, from Mazoe to Angola, is a 

 modification of this type (as proved by the skull), diflering from 

 clivosus in the more pronouncedly pandurate sella, the much 

 broadei' horse-shoe, the much smaller ears, and, by far the most 

 interesting, in the shortening of the third onetacarpal. This 

 last peculiarity is the same as that pointed out above, under 

 Rh. ferrum equinum : in the wing-structure Rh. darlingi differs 

 from Rh. clivosus quite in the same way as Rh. ferrum-equimmn 

 from Rh. affinis. It is a suggestive fact to find this peculiarity so 

 exactly copied by the South- African species. 



Rh. acrotis'\, from Egypt and Erythrea, is, externally, very 

 similar to Rh. clivosus ; also the wing-structure is the same. But 

 the tendency, in clivosus, towards an obliteration of p^ and p" has 

 been further developed by acrotis : it has completely lost both of 

 these teeth, thus being, in this particular respect, the highest 

 member of the whole gi-oup. Rh. acrotis is a " Rh. affinis " with 

 a dentition still more advanced than in ferrum-equinumi regidus. 



(3) Ethio2nan sj^ecies of the ferrum-equinum type. — Rh. aiigurX 

 is widely distributed, in several geographical races, over the 

 southern part of the Ethiopian Region : the Orange River tract, 

 [Natal, the Lower Zambesi. It is the closest existing relative of 

 Rh. ferrum-equimmi ; the skull, the nose-leaves, the wing-sti'ucture 

 are the same ; but the dentition is a trifle less advanced, and the 

 ears are smaller. 



We find the ferrum- equinimi type also further northwards in 

 Tropical Africa (Mombasa) : Rh. decheni ; the skull and dentition, 

 and all external characters of any importance, are as in augur ; 

 but the horse-shoe is broader. 



The area occupied by these two Ethiopian representatives of 

 the ferrum-equimmn type extends, broadly speaking, from the 

 Orange River to Mombasa. It is completely cut ofi" from any 

 other region inhabited by that type of Bat ; it forms a large 

 enclave bordered to the north and -west by vast tracts where no 

 representative of ferrum-equinum occurs ; we must go so far 

 away from South and Equatorial Africa as the Euphrates Yalley, 

 Syria, and Algeria before meeting with the closest relatives of 

 those Ethiopian species. Thus the question suggests itself, by 

 which way the ferruin-equinum type reached Tropical Africa, 

 and why its range there is now so peculiaily insulate. When 



* Andersen, Ann. & Mag. Nat. Hist. (7) xv. (1905) p. 70. 



t Andersen, op. cit. (7) xiv. (1904) p. 454; (7) xv. (1905) p. 73. 



X Andersen, op. cit. (7) xiv. (1904) p. 380. 



