368 FISHES. 



Second Family — Saueid^. 



Body oblong, with ganoid scales; veriehrm nx>t completely 

 ossified ; termination of the vertebral column homocercal ; fins 

 generally with fulcra. Maxillary composed of a single piece ; 

 jaws with a single series of conical pointed teeth. Branchioste- 

 gals .numerous, enamelled, the anterior broad gular plates. 



Extinct. Numerous genera occur in Mesozoic formations ; 

 one with, the widest range is Semionotus, with distichous 

 fulcra, from the Lias and Jura ; Sugnathus, with large 

 posteriorly serrated scales, and fulcra on nearly all fins; 

 Ceplienoplosus from the Upper Lias ; Macrosemius from the 

 Oolite ; Propterus, Ophiopsis, Fholidophorus, Pleuropholis, 

 Pachycormus, Oxygnathus, Ptycholepis, Gonodus, Bulepidotus, 

 Lophiostomits, etc. 



Thikd Family — STYLODOKTiDiE. 



Body rhombic or ovate, with ganoid scales; vertebrw not 

 completely ossified ; termination of the vertebral column homo- 

 cercal ; fins with fulcra. Maxillary composed of a single piece ; 

 jaws with several series of teeth, the outer ones equal, styliform. 

 Dorsal fin very long, extending to the caudal. Branchiostegals 

 numerous. 



Extinct. Tetragonolepis from the Lias (see Fig. 103, p. 

 207). 



Fourth Family — SpH^EODONxiDyE. 



Body oblong, with rhombic ganoid scales ; vcrtebroB ossified, 

 hut not completely closed ; homocercal ; fins with fulcra. 

 Maxillary composed of a single piece; teeth in several series, 

 obtuse ; those on the palate globular. Dorsal and anal fins short. 

 ■Branchiostegals. 



Extinct. The type genus of this family is Lepidotus, so 

 named from its large rhombic, dense, and polished scales. 



