196 GEOLOGICAL SUCCESSION OF ANIMALS. 



vertebrates. The fishes are no longer the sole representa- 

 tives of that department. Reptiles, Birds, and Mammals 

 successively make their appearance, but the Reptiles are 

 preponderant, particularly in the oolitic formation ; on which 

 account we have called this the Reign of Reptiles. 



482. The carboniferous formation is the most ancient of 

 the Secondary age. Its fauna shows, in various respects, a 

 great analogy with that of the Paleozoic epoch, especially 

 in its Tribolites and Mollusks.* Besides these, we meet 

 here with the first air-breathing animals, which are Insects 

 and Scorpions. At the same time, land-plants first make 

 their appearance, namely, ferns of great size, club-mosses, 

 and other fossil plants. This corroborates what has been 

 already said concerning the intimate connection that exists, 

 and from all times has existed, between animals and the 

 land-plants (399). The class of Crustaceans has also im- 

 proved during the epoch of the coal. It is no longer com- 

 posed exclusively of Trilobites, but the horse-shoe crabs also 

 appear, with other gigantic forms. Some of the Mollusks 

 seem also to approach those of the Oolitic period, particu- 

 larly the Bivalves. 



483. In the Trias period, which immediately succeeds 

 the Carboniferous, the fauna of the Secondary age acquires 

 its definitive character ; here the Reptiles first appear. 

 They are huge Crocodilian animals, belonging to a pecu- 

 liar order, the Rhizodonts (Protosaurus, Notosaurus, and 

 Labyrintliodori). The well-known discoveries of Professor 



* This circumstance, in connection with the absence of Reptiles, has 

 caused the coal-measures to be generally referred to the Paleozoic epoch. 

 But there are other reasons which induce us to unite the carboniferous 

 period with the secondary age, especially when considering that here the 

 land animals first appear, whereas, in the Paleozoic age, there are only 

 marine animals, breathing by gills ; and also, that a luxuriant terrestrial 

 vegetation was developed at that epoch. 



