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Show 118 MR. K. ANDERSEN ON BATS [May 16, the African coast of the Gulf of Aden. It is the closest existing relative of the Himalayan Rh. affinis : 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.2) ; the same proportionate length of the tail. But it is more advanced in dentition : p3 is not only external (as in affinis), but very often lost; p2, which in affinis is still in the tooth-row, is in clivosus external and very small. In short: Rh. clivosus is a " Rh. affinis " with ferrum-equinum dentition. The clivosus type has found its way very far into the Ethiopian Region. Rh. darlingi *, from Mazoe to Angola, is a modification of this type (as proved by the skull), differing from clivosus in the more pronouncedly panduiate sella, the much broader horse-shoe, the much smaller ears, and, by far the most interesting, in the shortening of the third metacarpal. 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-equinum from Rh. affinis. It is a suggestive fact to find this peculiarity so exactly copied by the South-African species. Rh. acrotis t, from Egypt and Erytlirea, is, externally, very similar to Rh. clivosus; also the wing-structure is the same. But the tendency, in clivosus, towards an obliteration of p3 and p2 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 group. Rh. acrotis is a " Rh. affinis " with a dentition still more advanced than in ferrum-equinum regidus. (3) Ethiopian species of the ferrum-equinum type.-Rh. augur % 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-equinum ; the skull, the nose-leaves, the wing-structure are the same ; but the dentition is a trifle less advanced, and the ears are smaller. We find the ferrum-equinum type also further northwards in Ti'opical Africa (Mombasa) : Rh. deckeni; 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-equinum type extends, broadly speaking, from the Orange River to Mombasa. It is completely cut off 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 Valley, Syria, and Algeria before meeting with the closest relatives of those Ethiopian species. Thus the question suggests itself, by which way the ferrum-equinum type reached Tropical Africa, and why its range there is now so peculiarly insulate. When * Andersen, Ann. & Mag. Nat. Hist. (7) xv. (1905) p. 70. f Andersen, op. cit. (7) xiv. (1904) p. 4 5 4 ; (7) xv. (1905)' p 73 x Andersen, op. cit. (7) xiv. (1904) p. 380. |