No. I.] ARRANGEMENT OF THE SAUROPSFDA. loi 



gia, etc. ; the same is to be found in Sphenodon. The differ- 

 ences between Champsosaiirus and Sphenodon, given by Dollo 

 (1. c, p. 159), are results of specialization of a Sphenodon-like 

 form. Champsosaurus retains the neurocentral suture, which is 

 lost in the adult Sphenodon. 



Dinosauria — Crocodilia — Ornithosauria — Aves. 



These four " orders " certainly form a natural group of the 

 Sauropsida. The Dinosaurs are the oldest of these. It is not 

 probable that Protorosaurus from the Permian is a Dinosaur, as 

 Huxley' was inclined to suppose, and as Seeley^ has quite lately 

 suggested. 



The Dinosauria form three well-distinguished groups.^ 



A. Carnivorous T>\x\os2inrs,,'^ Harpagosauria, Haeckel, 1866. 



I. Goniopoda, Cope, 1866 (Theropoda, Marsh, 

 1881). 



B. Herbivorous Dinosaurs, Therosauria, Haeckel, 1866. 



n. Orthopoda, Cope, 1866. 



1. Ornithopoda, Marsh, 1881. 



2. Stegosauria, Marsh, 1877. 



C. Crocodilian-like Dinosaurs, Sauropoda, Marsh, 1878. 



HI. Opisthocoelia, Owen, 1859.^ 



It is possible that the Ornithosauria took their origin from 

 true Dinosaurs ; but at present we do not know such a group 

 from which they could have originated. It may be that the 

 Dinosaurs and Ornithosauria had a common ancestor. 



' Huxley, T. H. On the classification of the Dinosauria, with observations on 

 the Dinosauria of the Trias. Quart. Journ. Geol. Soc. , Vol. 26, 1870, p. 37. 



^Seeley, H. G. T. Philipps. Manual of geology, theoretical, and practical. 

 Part I. London, 1885, p. 515. 



3 1 omit here the " Dinosauria " described by Owen in " Descriptive and illus- 

 trated catalogue of the fossil Reptilia of South Africa, in the collection of the 

 British Museum, London, 1876." Owen creates a new group, Tretospondylia : 

 Taptnocephalus with notochordal vertebrae. In the family Serratidentia he puts 

 the genera Fareiasaurus and Antliodon. Pareiasaurus shows characters of the 

 Sauropoda; Anthodon such of the Stegosauridae. But from the present material the 

 exact position of these forms cannot be determined. 



^ Baur, G. Der Tarsus der Voegel und Dinosaurier. Morph. Jahrb., Bd. vin., 

 1882, p. 452. 



* I retain the first name proposed by Owen, who put those " Saurians " among the 

 Crocodilia. It is a fact that these forms show more characters common to the Croco- 

 dilia than to the Orthopoda. 



