TRANSACTIONS OF SECTION D. 771 



numbers of other fruit-eating bats abound. Indeed it is difficult to imagine 

 one of these great bats, whose flight appears so slow and laboured compared 

 with that of all other species of Chiroptera, traversing 50, much less 500, miles of 

 unbroken sea — for, even if carried out to sea by a storm, their wings would 

 evidently collapse long before they had travelled half the distance ; on the other 

 hand it is quite out of one's power to understand their present distribution, except 

 on the old grounds of independent creation, without postulating a much closer 

 connection than Mr. Wallace appears disposed to admit between the island groups 

 in the Indian Ocean at a comparatively recent period. 



The above-noted facts lead to the following deductions, namely, that in the 

 first place a chain of islands sufficiently close to allow of the passage, not only of 

 the representatives of the genera of insectivorous bats referred to, but also of the 

 large slow-flying frugivorous bats, must have existed between Madagascar and 

 Australia ; and, secondly, that at a later period a temporary connection of a similar 

 kind lay between Madagascar and India. 



It may be said that such connection with India would also permit of the intro- 

 duction of insectivorous bats ; but it must be again remembered that volant insects, 

 on which such bats feed, are very scarce in oceanic islands, while tree fruit, which 

 forms the food of the frugivorous species, is usually abundant. Bearing these 

 facts in mind, it is necessary to suppose that the islands, assumed to have formed 

 the high-road for the insectivorous bats between Africa and Australia, must have 

 been sufficiently large to support volant insects ; while, on the other hand, a chain 

 of small coral islands, placed not too far apart, and provided only with a few 

 fruit-bearing trees, would have sufficed for the passage of the frugivorous species ; 

 and it appears more than probable that it was by such a chain that the ancestors 

 ■of the flying-foxes of India were introduced into that continent. 



A review of the above-noted statements lends strong support to the theory of 

 a continent, or series of large, closely connected islands, extending across the Indian 

 Ocean at a comparatively recent period from Madagascar to Australia, which, 

 •originally advanced by Mr. P. L. Sclater, F.R.S.. is still maintained by many most 

 important distributional facts. 



7. On the Geographical Distribution of the Laridcp, (Gulls and Terns), with 

 special reference to Canadian Species. By Howard Saunders, F.L.S. 



The author pointed out that, excepting in the case of the circumpolar and sub- 

 arctic species of Laridce, the Atlantic forms a barrier between the Gulls of the 

 Palsearctic and Nearctic regions ; and almost so with the Terns. This he instanced 

 by reference to some European species and their Canadian representatives. Owing 

 to the belt of warm water between the tropics in the Atlantic, hardly any Gulls, 

 and but few Terns belonging to the northern hemisphere, cross the equator ; but in 

 the Pacific, where the expanse of warm water is narrowed by the approximation of 

 the cold Humboldt's current, which runs from the Antarctic regions to the equator, 

 on the one side, and by the Japanese cold current, reaching nearly to the equator, 

 on the other, several species of Gulls which breed in the far north, winter in the 

 southern hemisphere. The Pacific coast of North and South America is inhabited 

 by various species of Gulls differing widely in coloration from those of the Old 

 World, with the exception of a single species found in Japanese and Chinese waters, 

 and which presented intermediate characteristics. The North Pacific was, more- 

 over, the home of Sterna aleutica, which partakes of the coloration of the typical 

 Terns and of those of the inter-tropical Sooty-Tern group. It was only in the 

 Pacific that the winter range of the circumpolar forked-tailed gull, Xema sabinii, 

 extended to the south of the equator ; overlapping the area between the Galapagos 

 Islands and the coast of Peru, the home, so far as is known, of the very rare X. 

 furcata, only three specimens of which are in collections. Nearly all the large 

 Gulls without hoods are found in the North Pacific and Bering Sea ; and there also 

 that peculiar marine genus, Rissa (the Atlantic representative of which, It. tridactyta, 

 "has no developed hind toe), shows an approach to the typical four-toed Gulls by 



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