42 BRITISH FOSSIL REPTILES. 



the animal, the fossil remains of which he figured in the work above cited, is exemplified 

 by the generic name which the extinct Reptile has subsequently borne.^ 



Baron Cuvier amply confirmed the conclusions to which the above-cited authors, 

 and, subsequently, Conybeare^ arrived, and introduced copies of figures illustrative of 

 their papers in the concluding volume of his great work on ' Fossil Remains. '^ 



In the same year Prof George Fred. Jaeger recognised fossils as Ichthyosaurian in 

 the Lias of Boll, to one of the plates in whose Work reference will be subsequently made.* 



Subsequent additions to the history of the genus Ichthyosaurus will be found in my 

 ' Report on British Fossil Reptiles,' in the volume of the British Association for the year 

 1839, 8vo., p. 86. 



Before entering upon the details of structure and specific characters I may remark 

 that whenever the antecedent representatives of a class or order may be known, to which 

 an extinct genus is referable, the characters of the genus should be compared with those 

 of its predecessors in such class, rather than with its successors or with existing forms, 

 to gain an insight into its true affinities.^ 



The Labyrinthodont order, prevalent from the Carboniferous to the Triassic forma- 

 tion, manifests the tendency to dermal or peripheral ossifications which was carried out 

 to greater extent in older and lower vertebrate forms. The Ichthyopterygian order, pre- 

 valent from the Liassic to the Cretaceous period, continues to show the supplementary 

 ' prosquamosals ' (Tabs. XIX and XX, fig, 1, 27') and ' postorbitals ' (ib. ib., 12); and 

 the vertebral centrums retain the biconcave character (Tab. XVIII, fig. 6). The 'foramen 

 parietale ' (Tab. XIX, fig. 1,/) is common in Carboniferous/ Permian, and Triassic 

 Reptiles ; and, in some, is larger than in Ichthyosaurus'^ whence it has been continued on 

 to modern Lacertilia, but has become obliterated in the Crocodilian order. Both diapo- 

 physes and parapophyses* appear in Reptilian vertebriE at the same geological period, and 

 are carried on in the Crocodilian modification of the class, but are lost in existing Lacertilia. 



' " We have retained in these observations the name Ichthyosaurus, originally applied to this animal 

 by Mr. Konig, of the British Museum, feeling convinced that on a full and careful review of its whole 

 structure it will not be found to possess analogies sufficiently numerous or strong with the peculiar organi- 

 sation of Proteus to authorise the change of this appellation into Proteosaurus, as subsequently proposed." 

 — Tom. cit., p. 563, Conybeare and De la Beche. 



" " Additional Notices on the Fossil Genera Ichthyosaurus and Plesiosaurus," ' Trans, of the Geolo- 

 gical Society,' 2nd series, vol. i (1824), p. 103. 



^ ' Recherches sur les Ossemens Fossiles,' 4to, tome Seme, 2de partie, 1824, p. 447, pi. ii. 



* ' De Ichthyosauri sive Proteosauri fossilibus specimiuibus in Agro Bollensi repertis,' 4to, 1824. 



5 Owen, ' Palaeontology,' 8vo, 1860, p. 206. 



^ " Ueber Arcliegosaurus Declienii, Goldf.," von Dr. G. Jiiger, 4to, ' Miinchen Abhandl.,' Bd. v, 

 1847, p. 415, tab. xxvi, fig. 1. 



' 'Descriptive and Illustrated Catalogue of the Fossil Reptilia of South Africa in the British 

 Museum,' 4to, 1876 ; Galesaurus pi. .xviii, fig. 8, '" ; Petrophryne, pi. xx, fig. 18, ^' ; Gorgonops, pi, xxi, 

 fig. 3, 7'; Dicynodon, Ptychognattius, Oudenodon, Kisticephalus, pis. Ixiv, Ixv; Procolophon, pi. xxiij 

 figs. 4, 8. 



^ Op. cit., Pareiasaurus, pi. x, figs. \, 3, d, p ; Dicynodon, pi. lii, fig. 1 ; pi. liii, fig. 3, d. 



