44 Department of Vertebrate Palceontology. 



12. Mastodon americanus, North American Pleistocene 



Elephant. 



This animal is executed from the skeleton in the American 

 Museum of Natural History, and it is characterized by being 

 partly hairy, in contrast with the extremely hairy northern 

 variety of the Mammoth, and in view of the probability that 

 all the more primitive elephants were coated with hair. It 

 has distinctly the low, fiat skull of the African Elephant, 

 whereas the Mammoth had the high, prominent forehead 

 characteristic of the Indian Elephant. The skeleton is also 

 distinguished by enormously large, projecting feet, larger than 

 in any existing species, and by the relative shortness of the 

 limbs, also a primitive feature. This restoration, therefore, 

 while based upon studies of the elephant, exhibits the charac- 

 teristic proportions which distinguished the Mastodon ex- 

 ternally. 



Originally executed for reproduction in Harper's Magazine, 1S97. 



13. Dryptosaurus (Laelaps), Carnivorous Cretaceous Dinosaur. 



In this and the four following restorations Mr. Knight was 

 guided largely by ideas and sketches given him by Prof. Cope 

 shortly before the latter's death. They are based upon speci- 

 mens in the Cope Collection now in the American Museum, and 

 upon restorations by Professor Marsh of related types. 



This Dinosaur, represented in the photograph as engaged in 

 combat, was of considerable size, about fifteen to twenty feet 

 in length, and well armed in teeth and claws. Prof. Cope con- 

 sidered that the long hind limbs and heavy tail indicated great 

 leaping powers, in spite of its large size, and the restoration is 

 made in accordance with this idea. Dryptosaurus was allied 

 to Ceratosaurus of Marsh and to the European Megalosaurus. 



Cope, Proc. Acad. Nat. Sci. Phila., 1866, 275; Proc. Am. Phil. Soc, 



XXX, p. 240, May, 1892. 

 M.\RSH, Dinosaurs of North America, pp. 157-163, pi. xiv. 



14. Elasmosaurus, Long-necked Cretaceous Plesiosaur. 



Elasmosaiirus was one of the largest of the marine reptiles 

 which inhabited the Cretaceous seas. It was related to the 



