586 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.59. 



National Museum and the American Museum of Natural History, 

 from the Morrison, Lance, and Belly River formations, and those 

 which were found to resemble it most nearly were from the Belly 

 River formation. No fewer than four unguals in the American 

 Museum of Natural History collections, except for their larger size, 

 were exact counterparts of the bone under consideration (compare 

 figs. 4 and 5, pi. 110). None of these, however, have been identified. 

 One of them is illustrated here together with the type to show their 

 close resemblance. While the observations recorded above may be 

 of little moment, it appears significant that two bones from widely 

 separated geological horizons should show such startling close resem- 

 blances, especially, since the Arundel fauna contains other members 

 that have unquestioned Upper Cretaceous affinities. 



ORNITHOMIMUS AFFINIS Gilmore. 



Plate 112, figs. 1 and 3; plate 113, figs. 1 and 3; plate 114, fig. 1. 



Ornithomimus affinis was founded 15 on a number of cotypes, 

 consisting of an astragalus, metatarsals, and other elements of the 

 hind feet. In 1888 16 those same bones were used by Prof. O. C. 

 Marsh as the cotypes of the species Allosaurus medius, all of which 

 excepting a tooth were subsequently referred by Lull l7 to the Ortho- 

 poda and to the new species Dryosaurus grandis. In a recent paper 18 

 I have shown that these cotypes do not pertain to the herbivorous 

 dinosauria but to the carnivorous Theropoda, and in all probability 

 to the genus Ornithomimus. The species name "grandis" having 

 been previously used, it became necessary to assign a new name and 

 the term 0. affinis was selected to designate this species. 



The recognition of an Ornithomimid dinosaur in the Arundel fauna 

 was entirely unexpected for previously representatives of the family 

 Ornithomimidae had only been known from the Judith River, Belly 

 River, Edmonton, Denver, and Lance formations of the Rocky 

 Mountain region, all Upper Cretaceous, while the Arundel on the 

 highest authority, has been regarded of Lower Cretaceous age. 

 Thus the range of this dinosaurian family is greatly extended both 

 geologically and geographically. 



Since these cotypes have been described in detail in a recent paper l9 

 it appears unnecessary to do more here than to call attention to those 

 features which demonstrate the Theropod nature of these bones, 

 followed by a summary of the reasons for assigning them to the 

 genus Ornithomimus. 



is Bull. 110, U. S. National Museum, 1920, pp. 137. 



»6 Amer. Journ. Sci., vol. 35, 1S88, p. 93. 



17 Lower Cretaceous, Geol. Survey of Maryland, 1911, pp. 183-186. 



w Bull. 110, U. S. National Museum, 1920, pp. 137-142. 



w Idem, pp. 137-142. 



