O, C. Marsh on the Remains of a new Enaliosaurian. 11 



These vertebrae of tlie Eosaurus, althougli the only remains 

 of the genus at present known, are so characteristic and well pre- 

 served that they afford considerable evidence in regard to the 

 structure and habits of the animal to which they belonged. 

 They indicate that this reptile, like the later Enahosaurians, 

 was of great size,* air-breathing, cold-blooded, and carnivorous; 

 that it was aquatic, and probably marine, inhabiting the sea or 

 estuaries ; or possibly, as might be inferred from the place of its 

 entombment, the mouths of rivers flowing into the sea.t The 

 flattened form of the vertebrae ; the great depth of their terminal 

 concavities ; the separate condition of the neural arch ; and its 

 short longitudinal extent at the base, — all are consistent with 

 the conclusion that the Eosaurus was capable of rapid progress 

 through the water in pursuit of its prey, which was probably 

 fishes ; and since it had then, according' to our present knowl- 

 edge, no superior in point of size, it must have reigned supreme 

 in the waters of the Carboniferous era. 



As the vertebrae which have been described in this paper were 

 discovered in 1855, they are, consequently, so far as the writer 

 is aware, the first osseous remains of a true air-breathing Saurian 

 from the Coal formation ; and the only Enaliosaurian remains 

 yet obtained from below the Upper Triassic. Occurring as 

 they do in Palasozoic strata, they add another to the arguments 

 that have been brought against the so-called "Development 

 Theory ;" and they show with how great caution we should re- 

 ceive the assertions, so frequently and confidently made on nega- 

 tive evidence alone, of the exact date of the creation or destruc- 

 tion of any form of animal or vegetable life. They prove, more- 

 over, that during the deposition of the Coal-measures the atmos- 

 phere was sufficiently free from the destructive gases, which, as 

 many suppose, had contaminated it, to permit the existence of 

 a high type of air-breathing reptiles. This period was, in fact, 

 the foreshadowing of an age, then far in the future, when Rep- 

 tilian life should hold undisputed sway upon the earth, until in 

 turn supplanted by a higher and a nobler form of existence. 



estuary deposits, this -would not preclude the possibility of their containing marine 

 remains ; as the -waters from -which they -were precipitated -were undoubtedly so 

 connected with the sea that an occasional transfer of the inhabitants from one to 



