248 



THE EXTINCT BATRACIIIA, REPTILIA 



habit rivers and lakes. Trionyx, a well-known river type, is represented by three species; 

 none arc known to be marine. 



There remain the orders Pythonomorpha and Sauroptcrygia, none of whose members 

 exist at the present day. These were probably truly marine, as well as associated with 

 the estuary types already enumerated. 



It may be asserted that there is no systematic evidence to show that the ancient re- 

 presentatives of our fresh-water forms were not marine, and to this a partial assent may 

 be given. We may look to some other sources of evidence in explanation of the question. 



The most westward division of the Cretaceous, embracing the bed No. 1, of Meek and 

 Hayden, which contains abundant leaves, etc., of terrestrial plants, may have been more 

 entirely fresh than the others, as I have suggested, Proceed. Acad. Natl. Sci., 1868, 157.* 



The second, or Ripley clay, has produced few vertebrate; remains, the most important, 

 the Iladrosarus foulkoi, a terrestrial animal. The molluscs are largely marine. 



The third scries, embracing the lower green-sand bed, contains more; numerous verte- 

 brates, as Mosasaurus, Thoracosaurus, etc., bid;, as my friend, Jno. Smock, of the State 

 Survey, has observed, almost no tortoises. To this, one exception occurs in the Trionyx 

 halophilus, Cope, which is from near the Delaware and Chesapeake Canal, in Delaware, 

 from the lower bed. The species which are only known from these two clays and marls, 

 are as follows: 



From the Clays of No. I. 



Plesiosaurus lockwoodii. 



Ornithotarsus immanis. 



Hadrosaurus foulkoi. 

 From the Clays and Marl of the first bed. 



Elasmosaurus orientalis. 



Clidastes iguanavus. 



Mosasaurus fulciatus. 



Mosasaurus maximus. 



Mosasaurus dekayi. 



Trionyx halophilus. 

 Trionyx priscus. 

 Emys sp. 

 Beryx insculptus (fish). 



From the Rotten Limestone of Alabama. 

 Mosasaurus brumbyi. 

 Liodon congrops. 

 Clidastes propython. 

 Clidastes intermedins. 



The fourth series, embracing the second green-sand bed, contains the greatest number 

 of vertebrate species, distributed as follows : 



Sauroptcrygia, 2; Crocodilia, 10; Dinosauria, 4; Testudinata, 22; Pythonomorpha, 6. 

 The remains of these arc all found in the lower division of the green-sand bed, defined 



* T. A. Conrad and Prof. Newberry, bcliovo these bods to be Triassic; I have stated it as my belief, that some of 

 them are Jurassic. I am confirmed in this opinion by the discovery of a species of Asteracanthus, by Dr. G. J. 

 Fisher, of Sing-Sing, a genus known only in the Jurassics of the old world. 



