SUB-CLASS V 



GANOIDEI 



71 



Strepsodus, Young (Dendroptychms, Young; Archichthys, Hanc. and Atth.). 

 Large and medium- sized fishes with slender and somewhat curved teeth, 

 which are not compressed to sharp edges. S. scmroides, Binney sp., from. Coal 

 Measures of England, Scotland, and Ireland. Other species from LoAA'er 

 Carboniferous of Scotland, Ireland, and Nova Scotia. 



Ehizodopsis, Young {Dittodiis, Ganolodus, Characodus, Gastrodus, Owen), 

 (Fig. 128). Scales oval, with an extremely thin layer of punctate ganoine. 

 Teeth round in section, smooth. Vertebral axis with ring vertebrae. The 

 small type species represented by fine examples in the English Coal Measures. 

 Frao-ments in the Coal Measures of Silesia, Nova Scotia, and Illinois. 



Gyroptychius, M'Coy ; Tristichopterus, Egerton ; Eusthenopteron, Whiteaves ; 

 Polyplocodus, Pander ; Sauripterus, Hall. Devonian and Old Eed Sandstone ; 

 Europe and North America. 



Family 3. Osteolepidae. Smith Woodward. 



Body slender, covered with rhombic ganoid scales. Eing vertebrae at least in the 

 caudal region. Paired fins with a short, obtuse lobe. Teeth coniccd, only externally 

 folded at the base, as in Rhizodontidae. Devonian and Carboniferous. 



Osteolepis, Ag. (Tripterus, Triplopterus, M'Coy), (Fig. 129). Cranial roof 

 bones in advance of the parietals fused into a continuous shield, pierced by a 



Fig. 12y. 

 Osieolepis raacrole'pi.dotus, Ag. Lower Old Red Sandstone ; .Scotland (restoration after Pander). 



median frontal (pineal) foramen. An anterior median jugular plate present. 

 Teeth round in section. First dorsal fin in front of the pelvic pair. Scales 

 smooth and punctate. 0. macrolepidoius, Ag., and 0. microlepidotus, Pander. 

 Lower Old Red Sandstone ; Scotland. 



Thursius, Traq. As Odeolepis, but first dorsal opposite pelvic fins. Lower 

 Old Red Sandstone ; Scotland. 



Diplopterus, Ag. Lower Old Red Sandstone ; Scotland. 



Megalichthys, Ag. (Centrodus, M'Coy ; Ehomboptychius, Young ; Ectosteorhachis, 

 Cope). Cranial roof bones in advance of the parietals rarely fused into a 

 continuous shield, without a median frontal foramen. 

 Teeth round in section. First dorsal fin nearly opposite 

 the pelvic pair. Scales smooth and punctate. Carboni- 

 ferous of Great Britain and North America. Lower 

 Permian of Texas. M. hibberti, Ag., the best known 

 British species from the Coal Measures. 



Glyptopomus, Ag. (Glyjytokiemus, Huxley), (Fig. 130). 

 Bones of cranial roof not fused together ; a median 

 frontal (pineal) foramen. External bones and scales 

 ornamented with irregular reticulating rugae or fused 

 series of tubercles. Upper Old Red Sandstone ; Scotland, possibly also 

 Belgium and Pennsylvania. 



Fig. 130. 

 Crlyptopomiis kin n a i r d i , 

 Huxley. Scale, enlarged. 

 Upper Old Red Sandstone; 

 Dura Den, Fifeshire (after 

 Huxley). 



