166 



Prof. H. G. Seeley. On the Classification [Nov. 24, 



Nat. Sci. Proc.,' November 13th, 3866, and December 31st, 1867; 

 ' Amer. Phil. Soc. Trans.,' vol. 14, Part I). He relied upon the 

 characters of the tarsus and the ilium ; and on their varied condition 

 divided Dinosaurs into three orders named Orthopoda, Goniopoda, 

 and Symphopoda. In the Orthopoda, the generic types associated are 

 Scelidosaurus, Hylaeosaurus, Iguanodon, and Hadrosaurus. And in 

 this group the relations of the tibia and fibula are compared to those 

 of modern Lizards, the proximal tarsals being distinct from each 

 other and from the tibia. The ilium has a narrowed anterior 

 prolongation. 



The Goniopoda is so named from the abrupt flexure of the tarsus 

 in the middle, which prevented the foot being extended in a line with 

 the leg, so that the a.nimals are plantigrade. The astragalus is distinct 

 from the tibia, but embraces its distal end. The anterior portion of 

 the ilium is dilated and plate-like. The genera in this group comprise 

 Megalosaurus, Lselaps, Ccelosaurus, &o. 



The Symphopoda comprises animals having the first series of tarsal 

 bones confluent with each other and with the tibia. The anterior 

 part of the ilium is dilated and plate-like. The type genera are 

 Ornithotarsus and Compsognathus. 



Professor Huxley rejected Professor Cope's groups because he 

 considered that the relations of the tarsal bones to the tibia and fibula, 

 which were supposed to characterise the Goniopoda, are also found in 

 the Orthopoda. I am not concerned to inquire how far this criticism 

 invalidates Cope's nomenclature, which does not rest wholly upon 

 tarsal characters for definition ; but it maybe remarked that Professor 

 Marsh subsequently obtained specimens which proved that there are 

 many Dinosaurs in which the astragalus does not embrace the tibia. 

 In place of Cope's three orders Professor Huxley offered a classifica- 

 tion founded upon characters of the teeth, mandible, ilium, femur, and 

 the absence or presence of dermal armour. He divided the order 

 Dinosauria into three groups or families, named Megalosauridai, 

 Scelidosauridce, and Iguanodontidoe. And it was f nrther proposed to 

 unite these families with Compsognathus into an order, Ornithoscelida 

 ('Geol. Soc. Quart. Journ.,' vol. 26, February, 1870). The characters 

 used for its definition are different from those relied upon by 

 Cope. The Megalosauridas is co-extensive with the Goniopoda. The 

 Orthopoda is subdivided, chiefly on details of tooth character and the 

 presence of dermal armour in the Scelidosauridse, and its supposed 

 absence in the Iguanodontidae ; but the grounds for the division 

 became less evident when Mr. Hulke found dermal armour well 

 developed in his Iguanodon Seelyi (' Geol. Soc. Quart. Journ.,' vol. 38, 

 p. 144, May, 1882). 



Subsequently Professor Marsh, in a series of memoirs dating from 

 1878 to 1884, proposed to divide the Dinosauria into four orders and 



