MEMOIR 



EXTINCT REPTILES OF THE CRETACEOUS FORMATIONS OF THE 

 UNITED STATES. 



INTRODUCTION. 



The present memoir consists of descriptions of remains of Reptiles discovered in 

 the Cretaceous Formations of the United States. It was the author's intention to 

 inckide an account of the fossil Fishes, of which he had the opportunity of examining 

 numerous specimens, so as to form a monograph of the extinct Vertehrata of the 

 Cretaceous period. These specimens are, however, in so many instances mingled 

 with others derived from Tertiary deposits that he has been led to defer an account 

 of them until he has the opportunity of ascertaining and separating those which 

 belong to the different formations. Other Vertebrata, Bird or Mammal, have not 

 been detected in the Cretaceous deposits of any part of America.^ 



^ I formerly attributed two species of Cetaceans to the Green-sand of the Cretaceous era of New 

 Jersey, which I now believe to be erroneous, and regret the more as I have been quoted in the 

 excellent works of Lyell (Princip. Geol. 9th ed. 145 ; Man. Elem. Geol. 5th ed. 254) and Dana 

 (Man. Geol. 473, 4T8) iu proof of the existence of such animals during the Cretaceous epoch. 



Dr. Harlan described a vertebra (Journ. Acad. Nat. Sci. Phila. VI, 232, Plate xiv, Fig. 1 ; Med. 

 and Phys. Researches, 282, Fig. 1), from Mullica Hill, N. J., which he considered to belong to a 

 species of Plesiosaurus. Having accidentally noticed the specimen in the museum of the Academy, 

 I recognized its cetacean character and referred it to a species with the name of PriscodelpMnus 

 Harlani (Proc. Acad. Nat. Sci. V, 327). As the formation at Mullica Hill belongs to the Cretaceous 

 epoch, it thus appeared as if evidence was obtained proving the existence of a Cetacean at that age. 

 Several other vertebrae, from the Marl of New Jersey, were at the same time referred to Priscodel- 

 pMnus grandaevus (Ibidem). The latter specimens have since been ascertained to have been 

 derived from a Miocene Tertiary deposit of Shiloh, Cumberland County. 



I have since had the opportunity of examining many Cetacean remains from the Miocene deposits 

 of New Jersey, and have been led to the conclusion that the vertebra of PriscodelpMnus Harlani is 

 a Miocene fossil which had become an accidental occupant of the Green-sand in which it was found. 



Not only have Miocene fossils occasionally found their way into the Green-sand of New Jersey, 

 but also the remains of more recent animals. The museum of the Academy contains remains of 

 Mastodon, Beaver, Reindeer, Deer, and Muskrat, from the Green-sand of Burlington and Camden 

 Counties. 



The tooth of a Seal, reputed to have been found in the Green-sand near Burlington, New Jersey, 



1 February, 1865. { 1 ) 



