100 BAUR. [Vol. I. 



they still have the complete lower cranial arch, lost in the other 

 groups ; they still have the intercentra, two Centralia in the 

 carpus, and the proatlas. Their shoulder-girdle is entirely 

 Lacertilian. 



It is probable that the Homoeosauria must be put together 

 with the Rhynchocephalia ; the shape of the jugal^ shows that 

 the lower arch was complete in Homoeosaums. 



I do not doubt that Homoeosaurus had intercentra between 

 all vertebrae. 



The Rhynchocephalia, together with the Protorosauria, to 

 which they are allied, are certainly the most generalized group 

 of all Reptiles, and come nearest, in many respects, to that 

 order of Reptiles from which all the others took their origin. 

 The embryology of Sphenodon (Hatteria) would be of the 

 highest importance for the understanding of the phylogenesis of 

 the Reptilia. 



The " Simwdosatiria." Dollo. 



The " Simoedosauria," containing the cretaceous and eocene 

 form, Champsosaurus, Cope, are considered by Dollo as a dis- 

 tinct order.^ 



I have to consider Champsosaurus, as Lydekker did, as a 

 specialized member of the order Rhynchocephalia. 



My principal proofs for that are, besides the common char- 

 acters given by Dollo (1. c, p. 158) : — 



First. The loose condition ^ of the otic bones.'* 



Second. The condition of the rib-articulation. 



Third. The articulation of the ribs in Champsosaurus is only 

 comparable with that of Sphenodon and Hyperodapedon. The 

 ribs of Champsosaurus are never placed entirely on the neura- 

 pophysis, as in the dorsals of Crocodilia, Dinosauria, Sauroptery- 



' Ammon, L. V. Uber Homceosaurus Maximiliani. Abhandlungen d. K. Bayr. 

 Akad. d. Wiss. Ii. CI. xv. Bd. ii. Abth., Miinchen, 1885, p. 12. 



* Dollo, L. Premiere note sur le Simoedosaurien d'Erqu^linnes. Bull. Mus. 

 Roy. d'Hist. Nat. Belg. Tome ni. 1884. 



' The loose condition of the otic bones, as described by Lemoine, is only found, 

 in a similar way, in Sphenodon. In young specimens, and even in old ones, the 

 sutures between the three bones are entirely distinct. 



* Lemoine, L. Etude sur les caractferes gdn^riques du Simoedosaure. Reims, 

 1884. 



