296 THE ZOOLOGIST. 



animals that have lived at a former period of the world's history, 

 but have at present no representatives, we shall find, — to again 

 quote our previous authority, " Among the Mammalia and birds 

 there are none (orders) extinct ; but when we come to the reptiles 

 there is a most wonderful thing : out of the eight orders or there- 

 abouts which you can make among reptiles one-half are extinct."* 

 Amphibia, however, certainly existed, and were apparently abun- 

 dant in the Carboniferous age ; and, as Mr. Thomson remarks, 

 " the food of adult amphibians usually consists of insects, slugs, 

 and worms." f We may surmise that many were arboreal in 

 their habits, and these, before the advent of the true reptiles and 

 birds, must have constituted the principal insect enemies. We 

 must also recollect that the Pterodactyles, or Flying Dragons, 

 during the long reptilian period, " played the role of the bats and 

 birds of the present day. "J The imperfection of the geological 

 record is, however, no argument against evolution, though it 

 seems strange it has not even been made of much more use by 

 some opponents. The struggle for life is an ancient one, but the 

 combatants have not always been the same. In Pliocene times, 

 as Prof. Owen has stated, " Bats, Moles, and Shrews were then, 

 as now, the forms that preyed upon the insect world in this 

 island. "§ The number of mammals which devour insects seem 

 sometimes overlooked, and this fact can be easily realized by 

 looking through the pages of any good treatise on the Mammalia, 

 and tabulating the nature of the food used by the different 

 animals. For the purpose of the present discussion it should be 

 remembered, as remarked by Mr. W. L. Sclater, that the con- 

 clusion is more than probable " that before the commencement of 

 the Tertiary epoch the whole world was, so far as is at present 

 known, inhabited by small insignificant mammals distinctly allied 

 to the marsupials. "|| 



Perhaps one of the inevitable faiths is that of the man of science 

 who neither disguises the necessity of the halt, nor disbelieves in 

 the certainty of the forward march, and these Carboniferous 



* ' Collected Essays,' vol. ii. p. 354. 



f ' The Study of Animal Life,' 2nd edit. p. 258. 



| ' Koy. Nat. Hist.' vol. v. p. 8. 



§ ' Hist, of British Fossil Mammals,' p. xxv. 



|| 'Geographical Journal,' vol. vii. p. 295, 



