Xi PALEONTOLOGY AND EVOLUTION 345 



comparatively scanty Eocene fauna yields examples 

 of the orders Cheiroptera, Insectivora, Rodentia, and 

 Perissodactyla ; of Artiodactyla under both the 

 Ruminant and the Porcine modifications ; of Carni- 

 vora, Cetacea, and Marsupialia. 



Or, if we go back to the older half of the Meso- 

 zoic epoch, how truly surprising it is to find 

 every order of the Reptttia, except the Ophidia, 

 represented ; while some groups, such as the 

 Omithoscelida and the Pterosauria, more specialised 

 than any which now exist, abounded. 



There is one division of the Amphibia which 

 offers especially important evidence upon this 

 point, inasmuch as it bridges over the gap between 

 the Mesozoic and the Palaeozoic formations (often 

 supposed to be of such prodigious magnitude), ex- 

 tending, as it does, from the bottom of the Car- 

 boniferous series to the top of the Trias, if not 

 into the Lias. I refer to the Labyrinthodonts. 

 As the Address of 1862 was passing through the 

 press, I was able to mention, in a note, the 

 discovery of a large Labyrinthodont, with well- 

 ossified vertebrae, in the Edinburgh coal-field. 

 Since that time eight or ten distinct genera of 

 Labyrinthodonts have been discovered in the 

 Carboniferous rocks of England, Scotland, and 

 Ireland, not to mention the American forms 

 described by Principal Dawson and Professor 

 Cope. So that, at the present time, the Labyrin- 

 thodont Fauna of the Carboniferous rocks is more 



