AND AYES OF NORTH AMERICA. !)!) 



As Leidy has referred the eastern and western herbivorous Dinosouria to one on the same genus, and as there is 

 much doubt as to whether the present animal is not one of them, I refer the latter here as an expression of the 

 probabilities of the case. 



PALAEOSCINCTJS, Leidy. 



This herbivorous genus is, as remarked by its describer, an interesting representative of the Hylaeosaurus of the 

 European Wealden. 



PALAEOSCINCUS COSTATUS, Leidy. 



Tr. Am. Phil. Soc., 1860, 145. 



Upper Jurassic Bad Lands of Judith River, Nebraska. 



ASTRODOjST, Johnston. 

 Amer. Journ. Dent. Sci., 1859. 



ASTRODON JOHNSTONI, Leidy. 



Cret. Kept. U. S., 10?, Tab. 



Cretaceous greensand, Maryland, (near Bladensburg. ) 



To a genus nearly allied to the present, should be referred the animal represented by 

 a large tooth discovered by Thomas Wright in the Island of Wight, described and fig- 

 ured by him in the Annals and Magazine Nat. History, 1852, p. 89. The creature has 

 been of larger size than the Astrodon Johnstoni, and apparently of a formidable nature. 



GONIOPODA, Cope. 



Proceed. Ac. N. Sci., Phila., 1666, 317. 

 Harpagmosauria Haeckel, 1866. 



Proximal tarsal bones distinct from tibia ; the latter closely embraced by the much 

 enlarged astragalus, on its inferior and anterior faces, forming an immoveable articulation. 

 Astragalus, with an extensive anterior articular condyle below, above in contact with the 

 fibula, which is much reduced, especially distally. Anterior part of the ilium dilated, and 

 plate-like. 



This group is named from the abrupt flexure of the ankle in the middle of the 

 tarsus, preventing the foot from being extended in line with the leg. 



It represents no doubt an early stage of developement of the Symphypoda, and is 

 remarkably similar in the same points in the structure of the posterior extremity, to the 

 embryo of the chick at about the ninth day. At that time the metatarsals of the bird are 

 distinct, proximally joined by a single tarsal element, which itself is separated by the artic- 

 ulation from a transverse piece composed of the confluent proximal tarsal series. The 

 latter element is not at this time united with the tibia, but it is in contact with the fibula. 



