156 



not yet proven, and for which further testimony is wanting. His 

 horizon as to what may be is continually being enlarged. 



The days probably were when those who had never seen or 

 heard of a bat would have said it was impossible for any animals 

 to fly, except such as had regular wings, like birds and insects. 

 Now, however, we know that not only bats, but several other 

 mammals, and even animals of the lizard kind, have the means of 

 transporting themselves through the air by lateral expansions of 

 the skin, sei-ving as wings ; the last novelty in this way being a 

 large tree frog, brought to Mr. Wallace when travelling in Borneo, 

 having the toes very long and the webs very largely developed, by 

 the help of which it had been "seen to come down, in a slanting 

 direction, from a high tree as it flew !"* 



What more startling also than the foct that, amongst insects 

 having trae wings, any should be found not using their wings for 

 the purpose of flight, but for the purpose of propelling themselves 

 through the water. Yet such is the case with a small hymenop- 

 terous insect, discovered a few years back by Sir John Lubbock ; 

 the fact being the more remarkable, from the circumstance that out 

 of 30,000 known species of hymenoptera, not one had previously 

 been discovered of aquatic habits. How antecedently improbable 

 therefore it was that any such existed ; and had such only existed 

 formerly, and been now extinct, and been found in the same fossil 

 state in which we occasionally find other insects, who, on looking 

 to its mere structure and characters, would have suspected (as 

 Sir John Lubbock remarks) that it was aquatic, t This is a fact 

 for the Palaeontologist. 



Again, there was a time when we should have said that those 

 animals which go through certain marked transformations before 

 attaining to maturity, like most insects and some reptiles, were 

 incapable of reproducing their species in the larval state. Of late 

 years, however, there has been " observed an asexual reproduction 

 in the lai-vge of a fly belonging to the genus Cecidomyia. This 

 reproduction was said to commence in autumn, to continue tlu-ough 

 the winter and spring, giving origin during the whole of this 

 period to a series of successive generations of larvae, until finally, 

 * Malay Arch, i. 59, with a figure. t See Linn. Trans., vol, xxiv., p. 135. 



