400 
XCTIXOPTERYGII. 
those of the pterygoid bones more or less granular. Gular plate 
present. Pectoral fins large and sickle-shaped, consisting of closely- 
apposed, unjointed and unbranched rays, of which the majority 
terminate successively at the oblique, trenchant anterior margin. 
The teeth of this genus from European Cretaceous formations 
were originally referred by Agassiz (Poiss. Foss., Eeuill. 1835, 
p. 55) in error to Saurocephalus of Harlan (Journ. Acad. Hat. Sci. 
Philad. vol. iii. 1824, p. 337) ; while the pectoral fins were wrongly 
described as fin-rays of Ptychodus (Agassiz, ibid. vol. iii. 1837, 
p. 56). The mistake in the identification of the teeth was first 
pointed out by Leidy (Joe. cit. 1857), who, however, failed to recog¬ 
nize that the elongated rostrum belonged to the same fish as these 
fossils. The pectoral fin-rays were first proved to be not Elasmo- 
branch by Cope (Joe. cit. 1875), and their identity with Protosphy- 
rcena was subsequently determined both by Cope (in A. S. "Wood¬ 
ward, Proc. Geol. Assoc, vol. x. 1888, p. 321) and by A. R. Crook 
(Palaeontogr. vol. xxxix. 1892, p. 110). The best description of 
the head hitherto published is that by J. Felix (Zeitschr. deutsch. 
geol. Ges. vol. xlii. 1890, pp. 278-302, pis. xii.-xiv.); but neither 
Crook nor the present writer has observed any evidence of the 
so-called “ praedentale ” described by this author. The thickening 
of the alveolar border of the dentary bone is interpreted by Cope as 
an anomalous median element. 
Protosphyraena ferox, Leidy. 
1822. “ Undetermined,” G. A. Man tell, Foss. South Downs, p. 228, 
pi. xxxiii. figs. 7-9. 
1835-44. Saurocephalus lanciformis , L. x4gassiz (errore), Poiss. Foss., 
Feuill. p. 55, vol. v. pt. i. p. 102, pi. xxv. c. figs. 21-29. 
1844. Saurocephalus lanceolatus , L. Agassiz, ibid. vol. v. pt. i. p. 8 
(misprint). 
1850. Saurocephalus lanciformis, F. Dixon, Geol. Sussex, p. 374, pi. xxx. 
fig. 21, pi. xxxi. fig. 12, pi. xxxii.* fig. 1, pi. xxxiv. fig. 11. 
1857. Protosphyrcena ferox, J. Leidy, Trans. Amer. Phil. Soc. vol. xi. 
p. 95. 
1857. Xiphias dixoni, J. Leidy, ibid. p. 95. [Rostrum; British Mu¬ 
seum.] 
(P) 1860. Saurocephalus lanciformis , V. Kiprijanoff, Bull. Soc. Imp. 
Nat. Moscou, vol. xxxiii. pt. i. p. 666, ph x. tig. 4. 
1877. j Erisichthe dixoni , E. D. Cope, Bull. U.S. Geol. Surv. Territ. 
vol. iii. p. 823. 
1878. Erisichthe dixoni, W. Davies, Geol. Mag. [2] vol. v. p. 260, 
pi. viii. fig. 3. 
1878. Protosphyrcena ferox, E. T. Newton, Quart. Journ. Geol. Soc. 
vol. xxxiv. p. 789. 
