16 Transactions of the 



place them in a wholly different set. Thus we find mammals 

 which can fly (as those at present under consideration), 

 mammals which seem practically fishes, and live a purely 

 aquatic life (e.g., the Cetacea, or whales). There are also 

 some mammals of low type which approach very nearly to 

 reptiles.^ Then, again, we find, ainong birds, the ostrich, 

 which, besides being unable to fly, possesses various develop- 

 ments of its internal structure that show no small resem- 

 blance to those of mammals. Among reptiles, there is a 

 curious little animal which is provided with a membranous 

 development very much resembling that of the flying squirrel, 

 and by means of this it can launch itself for a considerable 

 distance through the air.^ Among the antediluvian reptiles 

 we find an order (the Pterodactyls) in which the flying power 

 was still more fully developed, perhaps as much as in the 

 bats. Then again, among the fish, we even find some which 

 possess the power of walking on dry land beneath a burning 

 sun, and even remaining five or six days without water f so 

 that ' a fish out of water' does not always apply. Flying fish 

 are too well known to need comment. This sort of law or 

 arrangement will be seen on closer examination to exist in 

 the smaller differences of genera and species, as well as in 

 the more general ones of which we have been treating, but 

 we have not at present time to follow this subject out, and so 

 will proceed to that in hand. 



There is a certain strange and not generally known 

 animal called the flying lemur, or Colugo, which lies on the 

 border-land between the Quadramana and the Cheiroptera. 

 While in many respects strongly resembling the lemurs 

 (which themselves are but an aberrant form of monkeys), the 

 Colugo is provided with a membrane uniting the limbs and 

 tail, with which it is enabled to fly, or rather float, a con- 

 siderable distance through the air. Like the bats, too, it is 

 in the habit of sleeping and resting suspended by its hinder 

 paws. I have mentioned this animal as a sort of introduc- 

 tion to the true bats, which must now be considered. 



In looking at the bat, we are naturally led, first, to con- 

 sider the means by which it is enabled to fly. ' This we find 

 to be a membranous prolongation of the skin of the flanks 

 and other parts, which stretches round the body. To support 



' The Monotremata ( Ornithorliynchus and Echidna) have distinct reptilian 

 aflB.nities. 



2 The ' Flying Dragon' {Draco volans). Vide a paper by J. F. M. H. Stone, in 

 this volume. 



' The Climbing Perch of Ceylon {Anabas scandens). 



