CHIMiERIDnS. 
Li ** 
6 / 
Ty_pe. Skeleton ; Palaeontological Museum, Munich. 
A species known only by a small skeleton, which exhibits the 
outer lateral aspect of the dentition. Head occupying somewhat 
less than one-quarter of the total length; tail rapidly tapering. 
Space between pectoral and pelvic fins about equal to the distance of 
the former from the end of the snout. Dorsal fin-spine compara¬ 
tively short and robust, its length about equal to the depth of the 
trunk at its point of insertion. Oral margin of mandibular tooth 
regularly and deeply sinuous; post-oral margin nearly parallel with 
the symphysial margin. 
Form, fy Loc. Lower Kimmeridgian (Lithographic Stone) : 
Bavaria. 
Not represented in the Collection. 
Ischyodus planus, Newton. 
1878. Ischyodus planus, E. T. Newton, Chimseroid Fishes Brit. Cret. 
Bocks (Mem. Geol. Surv.), p. 37, pi. xii. figs. 1, 2. 
Type. Mandibular tooth ; collection of Thomas Jesson, Esq. 
A species of large size, known only by the mandibular teeth. 
Mandibular tooth with a gently wavy oral margin (and beak pro¬ 
bably short) • beak-tritor single, laminated; outer tritors rudimen¬ 
tary ; median tritor large, occupying nearly half of the oral surface, 
and posteriorly situated. 
Form. S)' Loc. Cambridge Greensand: Cambridge. (?) Upper 
Chalk : Norfolk. 
48945. Fragment of mandibular tooth, doubtfully assigned to this 
species by Newton, op. cit. p. 38 ; U. Chalk, Norwich. 
Bayfield Coll. 
Ischyodus thurmanni, Pictet & Campiche. 
1843. Ischyodus brevirostris, Sir P. Egerton, Proc. Geol. Soc. vol. iv. 
p. 156 (name only). 
1843. Chimcera ( Ischyodon ) brevirostris, L. Agassiz, Poiss. Foss. vol. iii. 
p. 344 (name only). 
1843. Chimcera ( Ischyodon ) agassizii, L. Agassiz {errore), ibid. pi. xl. c. 
figs. 14, 15. 
1858. Ischyodon thurmanni, Pictet & Campiche, Foss. Terr. Cretace 
St.-Croix (Pal. Suisse), p. 76, pi. ix. fig. 8. 
1862. Ischyodus agassizii, W. H. Bensted (errore), Geologist, vol. v. 
p. 378. 
1867. Ischyodus bouchardi, H. E. Sauvage, Catal. Poiss. Second. Bou- 
lonnais (Mem. Soc. Acad. Boulogne-sur-Mer. vol. ii.), p. 81, pi. iv. 
fig. 6. [Mandibular tooth.] 
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