AND AYES 01' NORTH AMERICA. 99 As Leidy has referred the eastern and western herbivorous Dinosouria, to one on the SaTIIC genus, and a, there is inueh 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 ease. PALAEOSCINCUS, Leidy. This herbivorous genus is, as remarked by its deserther, an interesting representative of the Ilylaeoscurus of the European Wealden. PALAEOSCINCUS COSTATUS, Leidy. Tr. Am. Phil. Soc., 1860, 145. Upper Jurassic Bad Lands of Judith River, Nebraska. Amer. Journ. Dent. Sci., 1859. ASTRODON, Johnston. ASTRODON JOHNSTONI, Leidy. Cret. Rept. U. S., 102, 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 Astroclon Johnstoni, and apparently of a formidable nature. GONIOPODA, Cope. Proceed. Ae. N. Sei., Phila., 1666, 317. Harpagmosteuria Ilaeekel, 1800. 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 Symphypodu, 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.
