List of Casts, Models, and Photographs. 45 



European Plesiosaurus , which it resembled in shape, except in 

 the flattened tail. It is represented in the restoration as cap- 

 turing a young Portheus, one of the large, bony fishes of the 

 period. A skeleton in the Museum of the Philadelphia 

 Academy of Natural Sciences, and another more complete in 

 the Cope Collection (but both lacking the skull), served as the 

 basis for the restoration. The Plesiosaurs differed greatly in 

 the length and flexibility of the neck, as well as in size. 



Cope, Cretaceous Vertebrata, U. S. Geol. & Geog. Surv. Terrs., F. V. 



Hayden in charge. Final Report, II, pp. 75-88. 

 Dames, Abh. k. preuss. Akad. Wiss. Berlin, 1895, pp. 75-80; Natural 



Science, Jan., 1898, p. 48. 



15. Agathaumas, Three-horned Cretaceous Dinosaur. 



These herbivorous Dinosaurs were of great size and had 

 large heads armed with three horns, and a great projecting 

 crest or frill protecting the neck. The body may have been 

 covered with small bony plates (scutes). This restoration is 

 based on a reconstruction of the skeleton of Triceratops 

 prorsus b}^ Prof. Marsh. Agathaumas sphenocents Cope, 

 shown in the picture, is distinguished by the large anterior 

 median horn and small posterior paired horns. 



Cope, Amer. Nat., 1886, p. 716; 1892, p. 768. 



Marsh, Dinosaurs of North America, Ann. Rep. U. S. Geol. Surv., 1896. 



16. Naosaunis and Dimetrodon, Spine-backed Permian 

 Lizards. 



These ancient reptiles represent an early specialized branch 

 of the primitive Rhynchocephalians. Their most remarkable 

 character is in the enormously elongated dorsal spines of the 

 vertebra, with (in Naosaurus) or without (in Dimetrodon) 

 transverse bars of bone. The restoration is based on a num- 

 ber of incomplete skeletons in the Cope Collection. 



Cope, Proc. Amer. Phil. Soc, 1878, p. 512. 



Baur & Case, Morphology of the Skull of the Pelycosauria, Anatom. 

 Anzeig., Jena, 1897, XIII, p. 109. 



