W. JDavies — On Saurocephalus. 255 



was known only by isolated teeth, which are far from rare in 

 the Chalk and the so - called Upper Greensand of Cambridge ; 

 specimens also occur, though not so abundantly, in other British 

 Cretaceous deposits. Ultimately a fine fragment of a lower jaw 

 came into the possession of the late Dr. Bowerbank ; while a 

 portion of a maxilla was obtained by Mrs. Smith of Tunbridge 

 Wells, both being from the Chalk of Burham, Kent. 



These specimens and some detached teeth in his own collection 

 were figured by Mr. Dixon ; ' who also states that he has " a portion 

 of an upper jaw with two teeth," in his possession ; and following 

 Agassiz he refers these remains to the Saurocephalus lanciformis, 

 Harl. 



It may be stated here, that all these interesting and instructive 

 specimens from the respective collections of Dr. Mantell, Dr. Bower- 

 bank, Mrs. Smith and Mr. Dixon, have been obtained for, and are 

 now preserved in the National Collection. 



Mr. Dixon also figures^ and notes a bony rostrum, which had 

 been obtained by Sir Philip Grey-Egerton, whose practised eye 

 recognized it as the consolidated and prolonged prKemaxillse of the 

 same species of fish to which the remains under consideration 

 belong. Very recently, I have seen a paper published in 1857 by 

 Prof. Leidy, of Philadelphia,^ in which he contends that the teeth 

 referred by Agassiz to Saurocephalus lanciformis, Harl., do not belong 

 to the species described by Dr. Harlan under that name, but that 

 they appertain to a very different fish, and in support of his position 

 Prof. Leidy re-figures and describes the original specimen upon 

 which the species was founded. A glance at the figures is sufficient 

 to show that the remains of the English and American fishes, which 

 have hitherto been considered as generically and specifically the same, 

 do in reality belong to two distinct genera. It seems strange that 

 so important a paper should have been overlooked or been but little 

 known to English ichthyologists, as in all collections I have seen, 

 this particular form of tooth and also the rostral bones are invariably 

 labelled as Saurocephalus lanciformis, Harl. The isolated teeth and 

 jaws, figured in the respective works of Agassiz and Dixon, Prof. 

 Leidy refers to a Sphyreenoid fish which he names Protosphyrcena 

 ferox, and he further states, that the rostral bones have no rela- 

 tion to these jaws and teeth, but pertain to a Xiphioid fish, which 

 he designates Xiphias Dixoni. It is due to Prof. Leidy to state 

 that these conclusions were derived from the published figures 

 alone, and not from a study of the fossils. 



With a view of testing these conclusions preparatory to re- 

 labelling the specimens in the National Collection, I carefully ex- 

 amined and compared all the English types of the species which 

 have been figured, not only with each other, but also with many 

 other specimens, more or less perfect, in the same collection ; and I 



^ Geol. and Foss. of Sussex, p. 374, plates xxx. fig. 20, 21 ; xxxi. fig. 12 ; 

 xxxiv. fig. 11. 



2 op. cit. p. 374, pi. 32*, fig. 1. 



3 Remarks on Saurocephalut and its Allies, Trans. Am. Phil. Soc. vol. xi. p. 91. 



