CRETACEOUS FORMATIONS. 69 



constructed and appropriate name of Iclithyosaurus, suggested for it Ijy the estimable 

 and accomplished keeper of the Mineralogical Department of the British Museum, 

 Charles Konig, K.H., F.R.S. 



Remains of species of Ichthyosaurus are found in secondary strata from the Chalk 

 down to the Muschelkalk, and most abundantly in the Oolite and Lias. In my 

 ' Report on the British Fossil Reptiles,' I recorded the discovery of " portions of the 

 lower jaw with teeth of a large species of Ichthyosaurus from the lower Chalk between 

 Folkstone and Dover, which was closely allied to the Ichthyosaurus communis. And in 

 the description of the Fossil Reptilia in Mr. Dixon's work ' On the Geology of Sussex, 

 some teeth from the Chalk of Kent, now preserved in the Museum of William 

 Harris, Esq., F.G.S., are figured in T. XXXIX, fig. 10, where they are stated to 

 belong to the genus Ichthyosaurus, and to correspond so closely in form and size with 

 those of the Ichthyosaurus communis, that I did not presume, in the absence of any 

 knowledge of the skeleton, to pronounce them to belong to a distinct species. 



I have since been favoured with the opportunity of studying and comparing the 

 required parts for yielding more satisfactory characters, and have arrived at a convic- 

 tion of the distinction of the species of Ichthyosaur of the Chalk-epoch from that of 

 the Lias, which it most resembles in the general shape and proportions of the teeth, 

 a distinction first recognised by James Carter, Esq., M.R.C.S., of Cambridge, who 

 proposed for the species the name of Iclithyosaurus campylodon, at the ' Meeting of 

 the British Association' at that University in 1846, on the occasion of the exhibition 

 of some fine remains of the species obtained by him from the Lower Chalk, in the 

 vicinity of Cambridge, in 1845. Before describing these remains, I shall give an 

 account of the additional specimens from the locality whence I derived the first evidence 

 of the presence of remains of the Ichthyosaurus in the Cretaceous strata. 



Ichthyosaurus campylodon. Carter. Lower jaw. Tab. XXIII. 



In the operations upon the Chalk-cliffs connected with tiic Dover Railway, a 

 considerable proportion of the lower jaws and fragments of the ribs of a large Ichthyo- 

 saurus were brought to light ; they were dislodged from the hard gray chalk at the 

 end of the Round Down Tunnel, about two miles and a half from Dover, under the cliff, 

 four feet from the beach beyond " Shakespeare's Cliff," towards Folkestone. 



The specimens are now in the collection of H. W. Taylor, Esq., of Brunswick Place, 

 Brixton Hill, to whose kindness I am indebted for the present opportunity of describing 

 and figuring them. 



The principal portion consists of four coadaptable fragments of the left ramus of 

 the lower jaw, including nearly the whole of the dentary piece, and fragments of the 

 splenial and angular pieces, the whole measuring two feet seven inches in length, but 



