2U FOSSIL FISHES OF THE ENGLISH CHALK. 



tlie sjmplivsial teeth exliibit one main cusp, with not more than one pair of small 

 lateral denticles. In very 3'oung individnals the corresponding teeth have three 

 pairs of lateral denticles, those of the inner pair nearly as large as the main cusp. 



Fig. 68. Cestracion philippi, Cuvier ; jaw with dentition, slightly reduced. — Existing. 



]. Cestracion canaliculatus, Egerton. Plate XLV, figs. 1 — 5. 



1822. Balistes, G. A. Mantell (errore), Foss. Soutli Downs, p. 229, pi. xxxiii, figs. 5, 6 (iu part?). 



1843. Spinax major, L. Agassiz, Poiss. Foss., vol. iii, p. 62, pi. xb, figs. 8 — 14 (in part). 



1850. Cestracion canaliadatus, P. M. Gr. Egerton, in F. Dixon, Geol. Sussex, p. 365, pi. xxxii,* fig. 8. 



1850. Acrodvs cretaceus, F. Dixon, op. cit., p. 364, pi. xxx, fig. 13. 



1853. Cestracion canaliculatvs, P. M. G. Egerton, Quart. Journ. Geol. Soc, vol. ix, p. 281. 



1872. Bre^mnepliorus canalicuhifn.", P. M. G. Egerton, Figs, and Descript. Brit. Organic Remains 



(Mem. Geol. Surv.), dec. xiii, no. 9, pi. ix. 

 1883. Cestracion canaliculatus, C. Hasse, Neues Jahrb., vol. ii, p. 66. 

 1889. Cestracion canaliculatus, A. S. Woodward, Catal. Foss. Fishes B. M., pt. i, p. 334, pi. xi, 



figs. 24—27. 



Ti/jje. — Associated teeth from the Chalk of Kent. 



Specific Chardcters. — Head nsnally attaining a length of about cm. Man- 

 dibular symphysis short. Principal lateral teeth with rounded ends, scarcely, if 

 at all, sigmoidally bent; the longitudinal keel sharp and raised into a median 

 eminence; the rugosity of the surface prominent. Anterior teeth with a pair 

 of broad lateral denticles; coronal surface smooth. Anterior dorsal fin-spine 

 much arched, placed approximately over the twenty-fifth vertebra. 



Description of Specimens. — The type specimen shows a few of the principal 

 grinding teeth in natural association ; and another fossil, described by Egerton 

 (1872), in the Willett Collection, Brighton Museum, exhibits similar teeth in the 



