204 Systematic Paleontology 



seems preferable^ however, in view of the rarity of the remains, to let 

 the matter rest in abeyance nntil further proof is obtained. 



Occurrence. — Aeundel Foemation. Bladensbnrg, Prince George's 

 County. 



Collections. — Yale Museum, Goucher College. 



Suborder ORTHOPODA 

 Family CAMPTOSAURIDAE 



Genus DR.YOSAURUS Marsh 



Dryosaukus geandis sp. nov. 



Plate XIX, Figs. 6, 7; Plate XX, Figs. 1-4 



Allosaurus medius Marsh (in part), 1888, Amer. Jour. Sci., ser. iii, vol. 

 XXXV, p. 93. 



Description. — The type material consists of a first phalanx of digit iv 

 of the hind foot (No. 5453, U. S. National Museum, cotype of Allo- 

 saurus medius), an astragalus (No. 5652, U. S. National Museum, ? co- 

 type of Allosaurus medius), a proximal phalanx of digit iii (No. 5684, 

 TJ. S. National Museum), the distal extremities of two metatarsals (Nos. 

 5684 and 5704 XL S. National Museum), an unnumbered ungual, and 

 the phalanx (No. 2609, Goucher College). 



Among the remains referred by Marsh to Allosaurus medius, the tooth 

 alone may be with certainty referred to the Theropoda ; the " first phalaiix 

 of the hind foot," surely, and the astragalus, probably, may be relegated 

 to the ornithopod dinosaurs of the genus Dryosaurus, and, together with 

 other material, become the cotypes of a new species. 



This species differs from the type of the genus, D. altus Marsh ' {Lao- 

 saurus), mainly in its greater size and proportions and in the character 

 of the astragalus. 



The left astragalus vieAved from below is somewhat hour-glass shaped, 

 narrowing toward the calcaneal facet. Viewed anteriorly, the upper 

 margin is seen to be broken away so that the sharp upward process 



^ Marsh, Amer. Jour. Sci. (iii), vol. xvi, 1878, p. 415, pis. ix, x. 



