RQITATTNA. 228 



2, o) may be referred with equal certainty to positions in the u})pcr jaw somewhat 

 farther Ijack. The elongated teeth which belong to tlie sides of the lower jaw — ■ 

 partly perhaps to the m)per jaw — have fine anterior serrations and the principal 

 cusp usually prominent (figs. -I-, 5) ; very rarely the principal cusp is less 

 attenuated (fig. G). Between all these variations there are so many intermediate 

 stao-es that there can be no doubt as to their belonging to one and the same 

 dentition. 



Horizons and Localities. — Zone of Bdcmni fella mncrouaia : Norwich. Zone of 

 Marsiipites : Thanet, Kent ; near Salisbury, Wiltshire. Zone of Micrasfer ror- 

 anguinum : Northfleet and Thanet, Kent ; Haling Pit, near South Croydon, Surrey. 

 Zone of Holaster planus: Borstal, near Rochester, Kent; Swaffham, Norfolk. 

 Turonian zones : Lewes, Sussex. Zone of Holaster snhglohosus : Glynde, Sussex ; 

 Burham, Kent; Betch worth, Surrey; Cherry Hinton, Cambridge. Zone of 

 Schloenhachia varians : Burham, Kent. Undetermined zones : Brighton and New- 

 timber, Sussex; Guildford, Surrey ; Charing, Kent. Also Cambridge Greensand. 



8nhor<ler TECTOSPONDYLI. 



Favilll/ S(^ITATTNID.1'1. 



Gen lis SaUATINA, Dumeril. 



Sqiiafhm, C. Dnnu'ril, Zool. Analvt., 1800, ]>. 102. 



Generic Characters. — Body depressed and flat, with Idunt snout and terminal 

 mouth ; paired fins very large, tlie basal part of the pectorals produced foi-wards, 

 1)ut not connected with tlie head; two dorsal fins on the slender tail. Teeth 

 conical and pointed, more or less laterally extended, but without denticles; outer 

 coronal face with a small median extension dowuAvards over the root ; root de- 

 pressed, not bifid. Three or four rows of teeth sinndtaneously in function ; 

 arranged in widely separated transverse series. Vertebral centra depressed, more 

 or less oval in transverse section. Shagreen in })laces enlarged or thickened. 



Tijpc f^pecies. — An existing fish, Squatina arir/p]iis. 



Bemarhs. — This genus ranges from the Upper Jurassic to the existing fauna. 

 Fine specimens occur in the Kimmeridgian Lithographic Stone of Bavaria and 

 Wiirteml)erg, and a nearly complete skeleton is known from the Upper Cretaceous 

 of Westphalia {Sqvatina haumhergensis, W. von der Marck, Pal^eontogr., vol. xxxi, 

 1885, p. 26 i, pi. XXV, figs. 1 — 5). Only teeth, vertebrae, and other fragments occur 

 in the English Chalk. 



