214 A. Smith Woodward — On a Second Species of Eurycormus. 



fused or semi-fused matter in the crust, partly consequent on the 

 repeated heating and cooling of the outer envelope and a lateral 

 thrust produced at each rise of temperature, with faulting and 

 wedging up to compensate for contraction at each fall of tempera- 

 ture, are in my view the potent causes of the external forms of the 

 earth as they have appeared from age to age. 



IV. — On a Second British Species of the Jurassic Fish 

 Eurycormus. 

 By A. Smith Woodward, F.L.S., F.G.S. 

 rpHE occurrence of a fish generically identical with Eurycormus of 

 I the Bavarian Lithographic stone, in the Upper Jurassic of 

 England, has already been indicated by the discovery of a well- 

 preserved head with some anterior vertebree in the Kimmeridge 

 Clay of Ely.' Only one specimen, however, has hitherto been 

 recognized ; and during a recent search for further evidence of the 

 fish among British fossils the present writer has thus been gratified 

 to find two more examples in the collection of the British Museum. 

 The one specimen was described many years ago by Sir Philip 

 Egerton, under the name of Macropoma Egertoni, and is said to have 

 been obtained from the " Gault, Speeton " ; the other specimen is 

 an obliquely-crushed head, with part of the squamation, found by 

 Mr. Alfred N. Leeds in the Oxford Clay of Peterborough. So far as 

 they can be compared, these two fossils agree in every particular, 

 even in detailed measurements ; hence they must be referred, for 

 the present at least, to one and the same species. 



Eurycormus Egertoni (Egerton). 



1844. Macropoma Egertoni, L. Agassiz, Poiss. Foss. vol. ii. pt. ii. p. 174 



(undefined) . 

 1858. ,, ,, P. M. G. Egerton, Figs, and Descript. Brit. 



Organic Eemains (Mem. Geol. Surv.), dec. ix. 



No. 10, pi. X. 

 1866. Eurypoma Egertoni, T. H. Huxley, ibid. dec. xii. p. 32. 



Description of Type Specimen. — The original description of the 

 type specimen published by Egerton is so unsatisfactory, and gives 

 so false an impression of some of the most important features of the 

 fossil, that it seems advisable to attempt a new account. The head 

 and anterior abdominal region are exposed in side view, as shown in 

 Mr. Dinkel's drawing [Joe. cit. 1858, pi. x. fig. 1); but the specimen 

 is so much distorted by crushing, and fi'actured in front, that the 

 apparent profile of the skull is entirely deceptive. The head is 

 compressed by accident from side to side ; the small left supra- 

 temporal plate and the larger post-temporal are displaced upwards 

 and forwards (the hinder margin of the post-temporal being described 

 as " occiput " by Egerton) ; and the greater part of the rostral region 

 is broken away, giving a false idea of steepness in profile in advance 

 of the orbit. The supra-temporals form a single pair of triangular 

 plates, and the occipital margin of the skull is evidently straight. 



1 Smith Woodward, " On a Head of Eurgconmis from the Kimmeridge Clay of 

 Ely," Geol. Mag. [3] Vol. VII. (1890), pp. 289-291, PL x. 



