HYBODUS. 3 



15. Woodward, A. S.— " On the Cranial Osteology of the Mesozoic Ganoid Fishes, 



Lejyidotns and Dapedim;' ' Proc. Zool. Soc.,' 1893, pp. 559—565, 



pis. xlix, 1. 

 16. "A Contribution to Knowledge of the Fossil Fish Fauna of the English 



Purbeck Beds," ' Geol. Mag.' [4], vol. ii (1895), pp. 14-5—152, pi. vii. 

 17. ■ "A Description of Ceyamnrns macrocephalas,'' ' Greol. Mag.' [4], a^oI. ii 



(1895), pp. 401—402. 

 18. " Note on the Affinities of the English Wealden Fish-Fauna," ' Geol. 



Mag.' [4], vol. iii (1896), pp. 69—71. 

 19. " On a new Leptolepid Fish from the Weald Clay of Southwater, Sussex," 



'Ann. Mag. Nat. Hist.' [7], vol. xx (1907), pp. 93—95, pi. i. 

 The following is the most important work on Wealden Fishes from the 

 European Continent. 

 20. Traquaie, U. H. — "Les Poissons Wealdiens de Bernissart," 'Mem. Mus. roy. 



d'Hist. nat. Belgique,' vol. vi (1911). 



SYSTEMATIC DESCRIPTIONS. 



Subclass EL A SMOBBA NOHIL 



■Order SBLAGIIIL 



Family CKSTCACioisTiDJi:. 



Genus HYBODUS, Agassiz. 



Hyhndus, L. Agassiz, Poiss. Foss., vol. iii, 1837, p. 41. 

 S^yhenonchus, L. Agassiz, ojj. cit., vol. iii, 1848, p. 201 (iu part). 

 Meristodon, L. Agassiz, ojj. cit., vol. iii, 1848, p. 286. 



Generic CJiaracters. — Trunk fusiform, moderately elongated; the first dorsal 

 fin opposite to the space between the pectoral and pelvic fins, the second in 

 advance of the anal fin. Snout not prominent but mouth inferior ; pterygo- 

 quadrate cartilage not articulated Avitli the preorbital region of the skull. Teeth 

 conical or cuspidate, the crown more or less striated, with one principal elevation, 

 and one or more lateral prominences on either side diminishing from the centre ; 

 root depressed, but not expanded inwards. Symphysial teeth few and large. 

 Notochord persistent ; slender ribs, not reaching the ventral border ; intercalary 

 cartilages almost or completely absent. Dorsal fin-spines longitudinally ridged 

 and grooved, the ridges not denticulated ; posterior denticles in two longitudinal 

 series, often alternating, not marginal but placed close together on a mesial ridge. 

 Shagreen consisting of small conical, radiately-grooved tubercles, sometimes two or 



