PEOF. OWEN ON THE SKTJLL OE MEGAIOSAtTRUS. 345 



mental ones, viz. the presence of an allantois and the non-develop- 

 ment of branchiae. 



By what Hunter denned as " lungs in the neck, called ' Gills,'" 

 he characterized his c Fourth Class ; ' and, in reference to the two 

 poles of the ' Amphibious ' division of the ' Fourth,' he observes, in 

 his quaint style, that they are " more fishifled than what the fish of 

 the first class ( Cetacea) are," op. tit. p. 27. De Blainville, enter- 

 taining similar views, proposed, in 1816, the name Ornithoidea for 

 the abranchiate, Ichthyoidea for the branchiate group *. 



The terms which Professor Huxley has invented for the two 

 groups previously defined and characterized by Hunter and myself 

 are as convenient as De Blainville's ; but it seems odd to speak of a 

 Lizard as a " Sauropsid," when it is not only like,, but is, a Saurian, or to 

 call a perch an " Ichthyopsid," which is not merely like, but is, a fish. 

 The terms "Abranchiates " and " Branchiates " appear to me to ex- 

 press an essential character of the two groups without suggesting 

 any absurdity. 



Eoturning to my proper subject, I would, finally, remark that, in 

 the summary of what I had learnt on fossil Reptiles in 1841, the 

 respective outward resemblance in the different orders to existing 

 vertebrate classes was briefly indicated — Pterodactyles to birds, 

 Ichthyosaurs to fishes, Dinosaurs to mammalian quadrupeds, &c. 

 But this was in no wise intended, or could be fairly construed, to 

 prejudice conclusions as to affinity founded on structure ; and those 

 which demonstrated the truer and deeper relations of Dinosaurs to 

 birds were given in detail in 1841 f . As to the dental and limb- 

 resemblances of extinct Saurians, I have since been enabled to show 

 that a group of triassic Rejptilia, the Theriodontia of the Karoo 

 formation, make a nearer approach to Mammalia, especially the 

 marsupial forms, than the later mesozoic Dinosaurs do, in outward 

 character £. 



Professor Huxley, however, asserts, in the Quarterly Journal of 

 the Geological Society, vol. xxvi. part 1, p. 13, note, that '-Prof. 

 Owen evidently attached no weight to the fact as indicating any affi- 

 nity of the Dinosauria with birds, as in his 'Report on British Fossil 

 Reptiles,' 1861, p. 102, he says that ' the Reptilian type of struc- 

 ture makes the nearest approach to Mammals in the Dinosauria.' " 



Other Fellows of the Society, besides myself, have been puzzled 

 to verify this statement ; and I have therefore added a summary of 

 what I did record ten years previously, and I have never changed 

 my opinion, of the near approach to Birds which the reptilian 

 type of structure makes in the Dinosauria, and more especially in 

 the genus and species which is the subject of the present paper. 



* Nouveau Bulletin des Sciences de la Societe Philomathique, 1816. 



t ' Reports of the British Association ' for that year. 



I In summing up the characters of Theriodonts I did not omit to notice that 

 their " sacrum was not limited, as in existing Reptiles, to two vertebras, but 

 was composed of five or six anchylosed vertehroe" (Quart. Journ. Geol. 

 Soc. 1870, p. 99). But this in no way affected the structural resemblance of 

 the sacrum of Dinosauria to that of birds, pointed out a quarter of a century 

 before. 



