EDAPHODON. 
183 
All the remains of Enelish Cretaceous Chimeroids known in 1878 were 
exhaustively described and discussed by EK. T. 
Newton, “The Chimeroid Fishes of the British 
Cretaceous Rocks” (Mon. [IV in Mem. Geol. Surv., 
1878). Since the publication of that work httle 
has been added to our knowledge of the Cretaceous 
genera and species, and there is not much new in 
the following pages devoted to them. 
The terms used in the description of the dental 
plates of Chimeeroids are explained in Text-figs. 
53—55, p. 184. 
Genus EDAPHODON, Buckland. 
Edaphodon, W. Buckland, Proc. Geol. Soc., vol. i, 1838, p. 687 ; 
Egerton, Quart. Journ. Geol. Soc., vol. ii, 1847, p. 351. 
Passalodon, W. Buckland, loc. cit., 1838, p. 687. 
Psittacodon, L. Agassiz, Poiss. Foss., vol. 111, 1843, p. 340. 
Eumylodus, J. Leidy, Extinct Vert. Fauna W. Territ. (Rep. 
U.S. Geol. Surv. Territ., vol. i, 1873), p. 309. 
Generic Characters. — Mandibular dental plate 
massive, without any thickening on its outer face ; 
its symphysial facette very broad; one anterior 
tritor present, and sometimes a smaller one below 
it; one median tritor, occasionally divided longi- 
tudinally, and two outer tritors. Palatme plate also 
Fia. 52. Chimera colliei, Bennett ; out- 
lines of mandibular dental plates in 
outer side view, nat. size, to show 
variations in shape in different indi- 
viduals.—Existing in Pacific Ocean. 
After B. Dean. 
very massive, without outer thickening ; three tritors present, two being inner and 
one outer. Vomerine plate more or less triangular in side view, with tritors on 
the oral margin; post-oral region laterally expanded, without any thickening. 
Type Species.—Hdaphodon bucklandi (Agassiz, Poiss. Foss., vol. in, 1843, 
p- 351, pl. xl d, figs. 1-—4, 9—12, 19—24) from the Middle Eocene of Bracklesham 
Bay, Sussex. 
Remarks.—This is a typically Cretaceous and Eocene genus, which does not 
seem to have become extinct until the dawn of the Miocene period. Three species 
are distinguishable by mandibular dental plates from the English Chalk. 
1. Edaphodon sedgwicki, Agassiz. Plate XXXIX, fig. 3. Text-figures 53—55. 
1843. Chimera (Psittacodon) sedqwickii, L. Agassiz, Poiss. Foss., vol. 111, p. 349, pl. xl, figs. 17, 18. 
1843. Ischyodus sedgwicki, P. de M. G. Egerton, Proc. Geol. Soc., vol. iv, p. 156. 
1847. Edaphodon sedgwicki, P. de M. G. Egerton, Quart. Journ, Geol. Soe., vol. iii, p. 352. 
