20 BULLETIN 34, UNITED STATES NATIONAL MUSEUM. 



eiideavoretl to include all the works in wbioU the Batracbia and their 

 internal and external relations have been expressly considered and new 

 views introduced. The system which appears to the writer to express 

 most fully the natural relations of the contents of the class is presented 

 in the following jiages. But I devote u few words to nomenclature. 



The earliest name for a given conception derived from individuals is 

 adopted. Species must be defined or figured ; genera and all higher 

 groups must be defined, since figures can not express the generaliza- 

 tions such names are intended to represent. As the conception of the 

 extent of a genus varies with discovery, it is impossible to require that 

 the definition accompanying its earliest name shall be necessarily exact, 

 so that a bona fide definition is all that is obligatory, according to the 

 rules. In the case of the higher groups the case is different. It has 

 been customary to require tbat the definition accompanying the name 

 adopted shall correspond with the thing adopted. If tbe definition 

 does not so correspond, tbe name has generally remained unused. Such 

 names are the Mutabilia and Immutabilin, Caducibrancbiata and Peren- 

 nibranchiata, which have been applied to systematic ideas not in corre- 

 spondence with tbe true relationsbips of tbe members of tbe Batracbia. 

 They have fallen accordingly into disuse. Such are also tbe so called 

 orders Emydosauria and Saurophidia. The division then receives the 

 name which was first applied to it, and not to something more or less 

 corresponding to it on ommission or addition of contents, Tbe rank as- 

 s'gned to such division is immaterial; tbe idea of the division itself is 

 everything. 



Applying these principles to the vertebrates which form the subject 

 of this book, I find the following to be the names to be adopted. I find 

 that Brongniart first perceived the correct limitation of the Batracbia, 

 and that in 1800 he gave it that name. In this he was followed by La- 

 treillein 1801; by Daudin, in 1802-3; byDumeril,in 1801 ; by Lamarck, 

 in 1809; by Cuvier, in 1800 and in 1817; by Merrem,in 1820; by Harlan, 

 in 1825; by Dumeriland Bibron, in 1841; and by various modern writers 

 since that date. The name Amphibia I find first used by De Blainville 

 in 1816 as interchangeable with the name Nudipelliferi, and also as a 

 subdivision of itself equal to the Perennibrancbiates of some later au- 

 thors. Tbe name is first definitely adopted by Latreille in 1825, a quar- 

 ter of a century after the introduction of tbe name Batracbia. lie is 

 followed after a long interval by Haeckel in 18GG, who, however, uses 

 tbe name Amphibia as interchangeable with Batracbia. It is exclu- 

 sively used by Huxley and by Gegenbaur, and by a number of modern 

 naturalists, chiefly anatomists. From the above record it is quite evi- 

 dent that tbe proper name for this class is Batracbia. 



Tbe true classification of the contents of the class was of much later 

 discovery. Tbe tailless division was recognized, it is true, by the earlier 

 authors; and, first of all, in 1708 by Laurenti. who called it tbe Salientia 

 and gave it a definition. This name must be therefore retained. The di vis- 



