SÜB-CLASS V 



GANOIDEI 



85 



Fig. 151. 



Pholidopleums typus, Bvonn. Keuper ; Raibl, Carinthia. 

 2/3 nat. size (after Kner). 



series short and very deep on the flank, those on the back and ventral 



region longer than deep. Dorsal and anal fins delicate, elongated, and low, 



directly opposed on the hinder part of the caudal region. Caudal fin ex- 



ternally homocercal, slightly forked. Trias ; Raibl, Carinthia. 



Pleuropholis, Egerton. Upper Jurassic (English Purbeck Beds, and French 



and Bavarian Lithographie 



Stone). P. egertoni, Wagn. 

 Pholidophorus, Ag. (Figs. 



152, 153). Body shaped like 



a carp. Scales thin, deeper 



than long on the flank, en- 



amelled, smooth or finely 



striated and serrated. Small 



dorsal fin opposed to the pelvic 



pair. Caudal fin externally homocercal, deeply forked ; a large, unpaired 



dorsal scale often at its base. Com- 

 mon in the Alpine Trias of Raibl 

 (P. bronni, Kner) and Seefeld ; in 

 the Lias of Lyme Regis (P. bechei, 

 Ag., P. lim- 

 batus, Ag.), 

 Whitby, Cal- 

 vados, Wür- 

 temberg, and 

 Bavaria (P. 

 germanicuSj 

 Quenst.) ; in 

 the Lithogra- 

 phie Stone of 

 Bavaria and 

 France ; in 

 the Purbeck 



Fig. 152. 

 Phali(1oj>hori(s striolaris, Ag. Head, iiat. size. Upper 

 Jurassic (Lithographie Stone) ; Bichstädt. cl, Clavicle ; 

 fr, Frontal ; iop, Interoperculum ; md, Mandible ; mx, 

 Maxiila ; na, Nasal ; op, Operculuni ; pa. Parietal ; pmx, 

 Premaxilla ; pop, Preoperculuni ; psph, Parasphenoid ; pt, 

 Post-temporal ; sd, Supraclavicle ; so, Snborbitals ; sop, 

 8uboperculum. 



Pholidophorus p^isilltis, A^ 

 Ehaetic ; Seefeld, Tyrol. 

 Xat. size. 



Beds of England and Lower Jura of the Black Hills, South Dakota. 



Isopholis, Zittel. As Pholidophorus, but scales of equal size and rhombic. 

 Pectoral and anal fins large. Lithographie Stone of Bavaria and France. 



Family 6. Pycnodontidae. Agassiz. 



Trunk laterally compressed, very deep, oval. Notochord persistent. Bibs, vertebral 

 arches, and spines well ossified. Opercular apparatus incomplete, with one or two 

 branchiostegal rays. Premaxilla with two to four prehensile front teeth ; maxilla 

 thin, deepened behind, toothless ; palatine aiid vomerine bones fused together, usually 

 with five longitudinal series of round or oval grinding teeth; splenial of mandible 

 large, with coronoid process, and three, four, five, or more rows of grinding teeth ; 

 dentary small and terminal, fitting in a groove of the splenial, and bearing two to four 

 prehensile front teeth. Branchial arches with very numerous, closely arranged, bony 

 filaments. Clavicle broadly ovate at the lower end. Fin fidcra ahsent. Pelvic fins 

 small. Dorsal and anal fins much extended. Scales deeper than long, with a 

 thickened, ridge-like anterior margin. Lower Lias to Upper Eocene. 



Gyrodus, Ag. (Figs. 154-157). Trunk completely covered with scales. 



