360 Systematic Paleontology 



Suborder TECTOSPONDYLI 



Superfamily MASTICURA 



Family MYLIOBATIDAE 



Genus MYLIOBATIS Dumeril 

 [In Cuvier, Regne Animal, tome ii, 1817, p. 137] 



" Head free from the disk ; so-called cephalic fin single. Teeth large, 

 flat, sexangular, tessellated, arranged in seven antero-posterior series. 

 The dentition of the upper jaw strongly arched antero-posteriorly, that of 

 the lower jaw quite flat. Dental crown smooth or slightly striated; 

 attached surface of root longitudinally ridged and grooved. Except in 

 very young individuals — in which the teeth are all approximately of equal 

 size — the median row is relatively very broad, while the teeth of the three 

 lateral series of each side are rarely broader than long. Tail with a dorsal 

 fin near its root, generally with a posteriorly situated barbed spine. 



" The relative proportions of the median teeth vary with the age (or 

 size) of the individual, the breadth gradually becoming greater with 

 respect to the length, and in determining the fossil teeth it is necessary to 

 allow for this change." — Woodward, 1889. 



The Eagle Eays extend from the late Cretaceous to the Recent. A very 

 large number of fossil species based on the dental pavement and caudal 

 spines have been described especially from deposits of Tertiary age. 



Myliobatis obesus Leidy (?) 



Myliobatis rugosus Leidy, 1855, Proc. Acad. Nat. Sci., Phila., p. 395 (non 



Meyer, 1844). 

 Myliobatis obesus Leidy, 1855, Proc. Acad. Nat. Sci., Phila., p. 396. 

 Myliobatis obesus Leidy, 1877, Jour. Acad. Nat. Sci., Phila. (II), vol. viii, 



p. 236, pi. xxxi, figs. 6-10; pi. xxxiv, fig. 44. 

 Myliobatis obesus Smith Woodward, 1889, Cat. Fossil Fishes Brit. Museum, 



pt. i, p. 123. 

 Myliobatis rugosus Hay, 1902, Bull. U. S. Geol. Survey, No. 179, p. 320. 

 Myliobatis obesus Fowler, 1911, Bull. 4, Geol. Survey of New Jersey, p. 93, 



fig. 48. 



Description. — " Dental plate arched in form, composed of four median 

 teeth and at least a row of lateral teeth each side. Enamel surface in 



