1883.] NATURAL SCIENCES OF PHILADELPHIA. 9t 



ON THE CHARACTERS OF THE SKULL IN THE HADROSAURID^. 

 BY E. D. COPE. 



In the year 1841, Professor Owen^ distinguished the Dinosauria 

 from other reptiles, as an order characterized by the structure of 

 the sacrum, the limbs, and tlie articulations of the ribs with the 

 vertebrae. The definition of the order remained without acces- 

 sion, until, in 1870, Prof. Huxley ^ determined the characters of 

 the pelvis. This important addition to our knowledge placed the 

 order on a firmer basis. No definitions were yet derived by 

 either author from the skull, so that the relationships ot the 

 Dinosauria still remained obscure. In 1861 Professor Owen de- 

 scribed part of the skull of a species of Scelidosaurus from the 

 English Lias. On this imperfect basis I ventured in 1870^ to 

 determine whether the Dinosauria are monimostylicate or 

 streptostylicate ; and I added to the definition of tne order, 

 "attached quadrate;" and later* " os-quadratum articulated with 

 its suspensorium b}' suture," thus placing these reptiles in the 

 monimostylicate series. This character, if found to be general 

 in the order, would distinguish it well from the Lacertilia, and 

 give a point of affinity to the Crocodilia. 



This order embraces a number of families. I at one time pf-o- 

 posed to refer them to three suborders,-^ and Huxley concluded 

 that they should be arranged in two suborders. •• Professor Marsh, 

 after showing that one of my three orders (Symphypoda) was 

 established on characters erroneously ascribed to its type by 

 previous writers, proposed to divide the Dinosauria into seven 

 suborders. He later'' regarded the Dinosauria as a subclass, and 

 divided it into five orders, the fourth of which is composed of 

 three suborders. The characters used by Marsh to define this 

 supposed subclass, do not differ from those previously developed 

 as^above cited, excepting that a number are introduced which 



V 



^ British Fossil Reptiles, . 



■^ Quarterly Journal of the Geological Society, p. 33. 



^ American Naturalist, 1871, p. 508. 



* Proceedings Amer. Assoc, Adv. Science, 1870 (1871), p. 233. 



^ Transactions American Philosophical Society, xiv, 1869, 90-99, 



" Quarterly Jour. Geolog. Soc, London, 1870. 



•^ Amer, Jour. Sci. Arts, 1882, p. 83. 



