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THE EXTINCT BATRACIIIA, REPTILIA 



COMPARATIVE OBSERVATIONS. 



The study of the early extinct vcrtehrata of this country possesses three points of in- 

 terest, to which the attention of students has been drawn. First: the period at which 

 given types of life have appeared on the earth; second: whether such types present ab- 

 rupt beginning and close, or exhibit a connection with others by intervening and only 

 partly subordinate forms; third: whether the; periods of existence of given types were 

 synchronous in different regions of the earth. 



With reference to the second point, it may be said, that, although investigations in the 

 held in question bring to light forms combining peculiarities once supposed to exist oidy 

 in distinct types, the primary divisions as herein defined have not yet been found 

 to be connected by forms not referable to any of them. If we suppose that such have ex- 

 isted, it is only by the analogy of forms discovered to be intermediate on a lower grade of 

 characters. 



The period of commencement of the Reptilian Orders has been generally believed to 

 be that of the Permian. No reptile has been discovered in and below the Coal Measures 

 in the old world, and nothing has been found in the new to invalidate this general state- 

 ment. Batrachia have left their tracks in the Subcarboniferous ; below this they are not 

 known; their remains first appear in the Carboniferous. Birds first appear in the Cre- 

 taceous, though they have; been chiefly found in Eocene and Miocene strata. 



With regard to the relative abundance of these types in the two continents, it may be 

 observed, that with present knowledge they appear to be nearly similarly developed, with 

 the following exceptions: The American formations are very poor in Ichthyopterygia and 

 Pterosauria, orders greatly developed in Europe ; while they contain abundant remains of 

 Pythonomorpha, which is represented in European beds by but few species. The subject 

 is, however, in its infancy. 



With respect to the synchronism of the Reptilian faunae here alluded to, the knowledge 

 of the subject is not sufficient to furnish; basis for an opinion, but I have elsewhere at- 

 tempted to show that similar faunae were quite as likely to prove successional, and succes- 

 sional fauna? synchronous, as the reverse. (See Origin of Genera.) 



As to the relations of times of appearance in tin; continents of Europe and North 

 America, we know too few species to be able to make more than a comparison which time 

 may invalidate. Of the periods of predominance of types a little more may be said. 

 Thus, both continents alike present a majority of the smaller Stegocephalous Batrachia 

 during Carboniferous time, and of the larger Labyrinthodonts during Triassic time. 



Our only Ichthyopterygia (not reckoning Eosaurus) appear in supposed Triassic beds : 

 those of the old world do not occur before the Jurassic (one is noted from the German 

 Trias). The old world Sauropterygia greatly predominate in the Jurassic, though a few 



