AND AVES OF NOKTII AMERICA. 



217 



occur in the Cretaceous. In North America they predominate in the Cretaceous. The- 

 codontia are Triassic in both continents ; and the Pythonomorpha are alike Cretaceous. 

 The serpents are in neither region older than Eocene. 



Among Testudinata, Trionyx is first Cretaceous in America, first Eocene in Europe. 

 Chelonoid Emydidse, also Cretaceous here, arc first Jurassic in Europe. In the latter 

 period the order has so far been best represented; those beds are rare in our country, but 

 if present, it could scarcely be more abundantly productive of them than is our Cretaceous. 



Among the Crocodilia, the amphiccelian division is especially Jurassic, not occurring in 

 the Cretaceous; our only genus was abundant in the latter period. The prococli are 

 characteristic of the tertiary in Europe, a very few being noted as from the upper Cre- 

 taceous. Here their chief abundance is in the Cretaceous, from which they extend to the 

 present time. 



The Dinosauria are characteristic of the upper Cretaceous period in North America, 

 and of the Jurassic to a less degree. In Europe they characterize the Jurassic, and are 

 rare in the Cretaceous. Thus, of corresponding genera Leelaps is Tipper Cretaceous, Me- 

 galosaurus and Pocciloplcurum, Jurassic. Iladrosaurns, upper Cretaceous and Jurassic; 

 Iguanodon, Jurassic and lower Cretaceous. Astrodon and Hypsibcma middle Cretaceous; 

 Ilylasosaurus, Jurassic. Further, we have evidence of many Dinosauria in the Trias., by 

 their foot-tracks and the remains of Megadactylus, Clcpsysaurus and Bathygnathus, which 

 an; nearly related to the genera of the Trias of England and Germany. 



A * 



STRATIG RA PHICAL OBSERVATIONS. 



I. The Cretaceous of New Jersey. 



A full review of the vertebrate species from the Cretaceous of New Jersey, results in 

 the conviction that but few of them belong to types which arc necessarily marine, while 

 many of them are the representatives of the genera wl del i are at the present day purely 

 fresh-water. Taking them seriatim, it is obvious that the six Dinosauria arc terrestrial, 

 and if at all, but occasional swimmers. The eight Crocodiles have only fresh-water re- 

 presentatives at the present day. The shortness of the limbs of these reptiles is not 

 adapted to stemming the waves of the open ocean or an undefended coast, for any long 

 period; and this observation will apply to all marine vertebrates with separated digits 

 whose life is spent in the water, and who rely on their limbs for progression, unless their 

 bulk be such as to render them independent of the waves, or they are furnished with 

 wings. Thus, the marine turtles possess long oar-like limbs, while those of brackish and 

 fresh waters have short paddles of far less power. The limbs of the twenty-four species 

 found in New Jersey, are of the latter character, and all their modern representatives in- 



