SüB-CLASS V 



GANOIDEI 



81 



145). Trunk much laterally compressed, deeply fusiform or cycloidal. Ex- 

 terna! bones ornamented with tubercles and ridges of ganoine. Eye surrounded 

 by a complete ring of small quadrangular plates {co), behind which are from 

 five to eight postorbitals {so, cheek- 

 plates). The supra-temporal plates {st) 

 also numerous. Operculum, suboper- 

 culum, and interoperculum large, 

 arranged in an arch. Preoperculum 

 narrow, almost or completely covered 

 by the postorbitals. A median gular 

 plate between the laminar branchiostegal 

 rays. Fin-fulcra A-shaped, the two 

 halves being f used at the apex. Pectoral 

 and pelvic fins small ; dorsal and anal 

 fins much extended and opposed ; caudal 

 fin slightly forked. Scales on the middle 

 of the flank deeper than broad ; no 

 prominent ridge scales ; all the scales 

 thick and enamelled, sometimes tuber- 

 culated. The earliest species in the 

 Alpine Trias (Seefeld, St. Cassian). 

 Common in the Lower Lias of England 

 and the Upper Lias of Würtemberg 

 (Boll, Holzmaden), Bavaria (Banz), '^i^l^rT^T^^fn F^oSaiTtrinSSe" 



Northern France (Calvados), {D. pholi- culum; ma;, MaxUla; na, Nasal; op, Operculum 



Fig. 145, 

 Head of Dapedius. ag, Angular ; hr, bulai plate 



7, i r\ 1 1 r\ j^ \ AI or, Orbit ; p. Parietal ; pmx, Premaxilla ; vt, Post 



aOtUS, Ag. ; JJ. CaelatUS, C^Uenst.). Also temporal; sei, Supraclavlcle ; so, Suborbitals ; so}), 



round in the Gondwana Beds of faÄraqualri ''' '^^"""^"'"'' ''' Supratemporal 



India. 



Heterostrophus, Wagner. Lithographie Stone (Upper Jurassic) ; Bavaria. 



Cleithrolepis, Egerton. Hawkesbury Formation ; New South Wales. 

 Karoo Formation ; Orange Eiver Colony. 



Tetragonolepis, Bronn {Pleurolepis, Quenst.). Small oval or almost cycloidal 

 fishes, laterally compressed, with small pectoral and pelvic fins. Dorsal and 

 anal fins much extended. Scales deepened on the flank, their front border 

 thickened and forming a vertical ridge. T. semicinäus, Bronn, from Upper 

 Lias, Würtemberg and Bavaria. Other species in the Upper Lias of England, 

 and the Kota Formation of the Deccan, India. 



Family 2. Semionotidae. Woodward.i 



Premaxilla, maxilla, and dentary with oUusely conical or chisel-shaped teeth ; 

 wmer, pterygo-palatine arch, and splenial with several rows of stouter hemispherical 

 teeth. All fins fringed with fulcra. Caudal fin hemi-heterocercal Scales thick and 

 rhomhic. Trias to Cretaceous. 



Colohodus, Ag. {Ästerodon, Münst. ; Tholodus, Meyer ; Dactylolepis, Kunisch). 

 Teeth hemispherical and irregularly crowded, usually with a mammiform eleva- 



^ Quenstedt, F. A., Ueber Lepidotus in Lias e. Tübingen, \M1 .—Sauvage, H. E., Memoire sur 

 les Lepidotus maximus et palliatus (Mem. Soc. geol. France, ser. 3, vol. I.), 1877.— Meyer, H. von. 

 Fossile Fische aus dem Muschelkalk (Palaeoutogr. vol. L), lS50.—Dames, W., Die Ganoiden des 

 deutschen Muschelkalks (Palaeont. Abhandl. vol. IV.), 1888.— Branco, W., Ueber eine neue 

 Lepidotus- Art aus dem Wealden (Jahrb. k. preuss. geol. Landesanst.), 1885. 



VOL. II G 



