THE 

 FOSSIL STURGEON OF THE WHITBY LIAS. 



A. SMITH WOODWARD, F.G.S., F.Z.S., 

 Of the British Museum {Xatural History), Sonih Keusittgton. 



For a long period the occurrence of large fibrous fish-bones in the 

 Upper Lias of Whitby has been well known ; and these fossils, as 

 pointed out by Mr. Simpson,^ are especially abundant in the bitu- 

 minous shale immediately above the jet rock. So long ago as 1S43 the 

 bones were submitted toAgassiz, who recorded them, without descrip- 

 tion, under the name of Gyrosteus //lirabilisf and the genus they 

 represented was placed among the somewhat indefinite extinct group 

 of Ccelacanths. In 1858 Sir Philip Egerton'' expressed the opinion 

 that the problematical remains were truly referable to a Sturgeon, 

 resembling Chondrosteus from the Lower Lias of Lyme Regis ; and 

 in 1876 Prof. J. F. Blake* published some desultory notes on the 

 bones, without making any very satisfactory comparisons. During the 

 last few years the writer of the present notice has had the privilege 

 of studying nearly all known examples both of the Whitby fish and 

 of its congener from Lyme Regis ; and the principal results of the 

 investigation were published last year by the Geologists' Association 

 of London.'^ It now appears that most of the bones can be 

 interpreted by reference to those of the common living Sturgeon 

 {Acipenser), with the aid also of certain known facts in the structure 

 of Chondrosteus. 



Beyond the fact that the jaws were toothless and the external 

 bones unornamented, little can as yet be ascertained concerning the 

 head of the fish. There seems to be an example of the great basal 

 {parasphenoid) membrane bone of the cranium in the Whitby 

 Museum (No. 338) ; and other elements perhaps referable to the 

 roof of the skull are also preserved in the same collection. The 

 most characteristic and easily-recognised bone, however, is the great 

 supporting element of the jaws, connecting them with the skull. 



^ M. Simpson, 'The Fossils of the Yorkshire Lias,' ed. 2, 1884, p. xiii. 



* L. Agassiz, ' Rech. Poiss. Foss.,' vol. ii, pt. ii (1843), P- I79- 

 3 P. M. G. Egerton, Phil. Trans., 1858, p. 883. 



*J. F. Blake, in Tate and Blake, 'The Yorkshire Lias' (1S76), p. 256, 

 pi. ii, figs. 2, 3. 



* Smith Woodward, ' On the Palaeontology of Sturgeons,' Proc. Geol. Assoc, 

 vol. xi ( 1889), pp. 32-36, figs. 2-7. 



April 1890. 



