No. 2389. FAUNA OF THE MARYLAND ARUNDEL— GILMORE. 583 



The complete fauna as recognized by Lull in 1911, and the re- 

 vised fauna as now determined by Gilmore are shown in the two 

 parallel columns below: 



Vertebrate Fauna of the Arundel Formation. 



Theropoda. 



Listed by Lull in 1911. Revised by Gilmore in 1921. 



Allosaurus medius Marsh. Dryptosaurus? medius (Marsh). 



Creosaurus potens Lull. Dryptosaurus? potens (Lull). 



Coelurus gracilis Marsh. Coelurus? gracilis Marsh. 



Ornithomimus affinis Gilmore 



Sauropoda. 



Pleuroceolus nanus Marsh. Astrodon nanus (Marsh). 



Pleuroceolus alius Marsh. Astrodon altus (Marsh). 



Astrodon johnstoni Leidy . Atrodon johnstoni Leidy. 



Orthopoda. 



Priconodon crassus Marsh. Priconodon crassus Marsh. 



Dryosaurus grandis Lull. 



Crocodylia. 



Goniopholis affinis Lull. Goniopholis? affinis Lull. 



Testudinata. 



Glyptoj)s caelatus Hay. Glyptops caelatus Hay. 



Pisces. 



Ganoid fish . Ganoid fish. 



Undetermined fish . 



The reasons for the above changes in the 1921 list are discussed 

 below under their respective headings in the order as given above. 



DISCUSSION OF THE MEMBERS OF THE ARUNDEL FAUNA. 



Order DINOSAURIA. 



DRYPTOSAURUS? MEDIUS (Marsh). 



Plate 110, fig. 2. 



This species was originally established by Marsh on a number of 

 cotypes, 8 all but one, the crown of a single large tooth (Cat. No. 

 4972, U. S. N. M.), Lull subsequently removed to the genus Dryo- 

 saurus, as the cotypes of the new species D. grandis Lull, 9 and 

 more recently referred by me 10 to the genus Ornithomimus. At this 

 time Dryptosaurusl medius rests on a single tooth shown in plate 110, 

 figure 2. So far as the type material is concerned it will always 



8 Amer. Journ. Sci., vol. 35, 1SSS, p. 93. 



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

 i° Bull. 110, U. S. National Museum, 1920, pp. 119-121. 



