326 WOODWARD : fossil fishes of the upper lias of WHITBY. 
Esox (the pike), several species of which have bony scales ; and it 
seems most akin to the Esox Leveriamts, or the Esox Chilensis.'' 
In 1832 a slab apparently of the Whitby Lias with scales of the 
same fish, was recognised by Agassiz in the Paris Museum, and this 
he provisionally named L. latissimus ; about the same time he found 
the caudal region of another fish, which he believed to be distinct, in 
the collection of M. Regley, of Paris, and this received the pro- 
visional name of Z. umbonatus. In 1834 Agassiz visited Whitby 
and identified the fossils he had examined in Paris with those 
originally described as pikes by Young and Bird, while three years 
later he published his detailed description of the species under the 
name of L. semiserratus. Specimens w^ere also identified in the 
museums of Scarborough, York, Newcastle, and Oxford, and in 
the private collections of Earl Fitzwilliam and Mr. Randyl, of 
Stockton. At the same time he hypothetically — and, as it now 
appears, erroneously — referred a very imperfect skull of the same 
fish in the Whitby Museum to another ill-defined form, the so-called 
Lepidotus rugosus ; but the latter name proves to have been applied 
chiefly to specifically indeterminable fragments of the squamation 
and opercular apparatus of members of the family Eugnathidse, one 
from Whitby (Proc. Yorks. Geol, and Polyt. Soc, vol. xiii., p. 35), 
the others from Lyme Regis. 
In 1849 Prof. W. C. Williamson described the microscopical 
structure of the scales ; but otherwise no further contribution to 
our knowledge of the AVhitby Lepidotus has been made within the 
last half century. A new detailed and illustrated description of 
the fish, in the light of the most recent research, has thus become 
requisite for comparison with the discoveries made in the Upper 
Lias of the European Continent since the studies of Agassiz were 
undertaken. The fine series of specimens now in the British 
Museum exhibit nearly all the principal characters of the species, 
and these suffice for the technical account of the skeleton of the 
fish which follows. 
The smallest detached skull (Brit. Mus., No. 35,556) is 
remarkable for the comparative smoothness of its external bones. 
It displays especially well the wdiole of the cranial roof except the 
