616 BATRACHIA. 



stages the circulation through the branchial apparatus is exactly the same as in the 

 fishes; but later pulmonary arteries make their appearance, lungs are developed, 

 and aerial respiration commences. 



The class has been divided into five orders, namely : Amphipneusta, Anura, Uro- 

 della, Abranchia, and Apoda. None of the Palaeozoic fossil families are referred to 

 any of these orders except the Cocytinidae, and the correctness of that reference is 

 exceedingly doubtful. All other Palaeozoic fossils are referred to orders which 

 have become extinct. The change, either by progression into higher classes of the 

 vertebrate kingdom, or by retrogression to an inferior state, is strongly marked. 

 The Urodella, to which the Cocytinidae are referred, have long, slender bodies, four 

 limbs, which are sometimes very small, and occasionlly the toes are furnished with 

 claws, and a long, persistent tail ; no external branchiae, but in some species there is 

 a branchial aperture on each side of the neck, within which are the branchial 

 arches, with their laminae ; lungs well developed, skin smooth, or covered with 

 warty prominences, and furnished with numerous glands, which secrete an acrid, 

 viscid fluid. In general form they resemble the lizards, which belong to the Rep- 

 tilia. The aquatic and land salamanders belong to this order. 



The first Batrachia are found in the Coal Measures. They increase rapidly in 

 numbers, and spread out in progressive evolution through the Permian Group, and 

 reach their highest development and largest size in the Triassic, and since that time 

 they have declined or retrograded, and now constitute a very inferior grade of the 

 Vertebrata. The Animal Kingdom has been divided into classes and orders upon 

 a basis which constitutes, as it is supposed, a natural system, and the more recent 

 study of embryology has demonstrated that this natural system corresponds with 

 the phases of embryonic history in all, or nearly all, its 'parts, and the study of 

 Palaeontology has proven beyond all peradventure that there has been a succession 

 of organic types from the earliest geological time to the present, which is stamped 

 upon the embryonic growth of living animals, and coincides with the grades estab- 

 lished by the natural system of classification. 



It follows that when the Palaeozoic orders are distinct from the living, the class 

 has been more comprehensive than the definition given by zoologists. Indeed, all 

 the fossils can not be strictly embraced within the prescribed limits of the Batrachia. 

 Many of them might be included within the Reptilia, because they combine Batra- 

 chian and Reptilian characters, and where the latter prevail probably they should 

 be classed with the Reptilia. Some of them, however, rise a step higher in the 

 animal system, and include Batrachian and Mammalian characteristics, and for this 

 reason it is urged by the evolutionists that the Mammalia descended from the Ba- 

 trachia, without having passed through the Reptilian stage. In other words, what 

 is here included is a comprehensive type of animal existence not limited by the 

 bounds which define the living Batrachia. 



The arrangement of the fossils into orders and families must be regarded as 

 provisional, and only approximating the present learning, for the following reasons, in 

 addition to those which will be apparent to the specialist : 1. There are several 

 synonyms of orders and families. 2. No one has published a complete classification 

 from which the author could compile the learning. 3. The author has never had 

 an opportunity to study the fossils of this class and have an opinion of his own to 

 assert or defend. 



