CARBONIFEROUS PERIOD. 343 



2. Animals. 



The animal life of the Coal measures is either (1) of land or fresh- 

 water origin ; (2) of brackish-water origin ; or (3) of marine origin; 

 and this is the first of the ages in which this distinction has been 

 proved by actual discovery to have existed, although probably a 

 fact in at least the latter half of the Devonian. Most of the lime- 

 stones and some of the sandstones and shales contain marine fos- 

 sils ; while, on the contrary, other deposits of sand and clay bear 

 evidence that they are not of the sea, any more than is the vegeta- 

 tion which covered the lands. 



The species include, among Protozoans, the little Fusulina of the 

 Ehizopod group, a shell consisting within of minute cells, and 

 related to the Nummulites of a later period. (See fig. 193, p. 164. ) 



Among Radiates, Corals and Crinoids, both Palaeozoic in type. 



Among Mollusks, numerous Brachiopods, Spirifers and Producti 

 being especially abundant; Conchifers ; Gasteropods, the species 

 for the most part without beaks to the shells ; Cephalopods of the 

 genera Nautilus, Goniatites, and Orthoceras. A Palaeozoic cast is appa- 

 rent throughout. 



But, while thus Palaeozoic in marine life, there is a new terrestrial 

 feature in the appearance of land-snails of the modern genus Pupa, 

 belonging to the highest group of Gasteropods, the Pulmonates. 



Among Articulates, there is, in nearly all of the departments, a 

 rise above the peculiarly Palaeozoic grade, for Trilobites are rare ; 

 and — what is of still more progressive aspect — there are Insects and 

 also Myriapods (Centipedes). 



Among Vertebrates, the fishes are all of Palaeozoic cast. They 

 comprise only Ganoids and Selachians. The Ganoids have vertebrate 

 tails, and the Selachians belong to the two extinct tribes of Ccstra- 

 cionts and Hybodonts, — the latter commencing with the Carbonife- 

 rous age. 



But there are also Eeptiles, air-breathing Vertebrates ; and these 

 are new types, prophetic of the Reptilian age, which was next to 

 follow. These early Reptiles* are (1) Amphibians, allied to the frog 



* The following are the general characteristics of Reptiles and of their sub- 

 divisions : — 



Reptiles are cold-blooded animals, like Fishes, but air-breathing, like birds 

 and quadrupeds. They are of low vital activity, with the temperature variable 

 and in general directly related to that of the surrounding medium. The verte- 

 brae differ from those of mammals in being convex and concave at the opposite 

 ends, and in a few cases concave at both extremities, approximating, in this last 



