228 GEOLOGICAL SUCCESSION OF ANIMALS. 



brates. Fishes are no longer the sole representatives oi 

 that department. Reptiles, Birds, and Mammals successive- 

 ly make their appearance, but 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 bears, in various respects, a 

 close analogy to that of the Palaeozoic epoch, especially in 

 its Trilobites 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 improved 

 during the epoch of the coal. It is no longer composed ex- 

 clusively of Trilobites, but the type of horse-shoe crabs also 

 appears, with other gigantic forms. Some of the Mollusks 

 seem also to approach those of the Oolitic period, particularly 

 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 peculiar order, the 

 Rhizodonts, (Protosaurus, Notosaurus, and Labyri?ithodon.) 

 The well-known discoveries of Professor Hitchcock, in the 

 red sandstone of the Connecticut, have made us acquainted 



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

 caused the coal-measures to be generally referred to the Palaeozoic 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 Palaeozoic age, there are only 

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

 vegetation was developed at that epoch. 



