22 



Fossil Fishes. 



Wall-case, 

 No. 5. 



There is a long series of fossil forms from the Old Red Sand- 

 stone, and in later deposits, referred by Prof. Huxley to the 

 Crossopterygidce. The first are known as the Holoptychiidce — having 

 large rounded bony scales deeply imbricating and sculptured on 



a 



». 





m 



)y>< 



"Wall-case, 

 No. 5. 



Wall-case, 

 No. 6. 



Wall-case, 

 No. 6. 



Fig. 49.— Holoptychius, Old Red Sandstone, Fifeshire (after Huxley). o, paired 

 pectoral fins ; b, pelvic fins ; c, the anal fin ; d, anterior dorsal fin ; e, posterior dorsal 

 fin. 



their exposed surfaces. The skeleton is not known ; most probably 

 it was notochordal. They only occur in the Old Red Sandstone, 

 and are represented by the genera Glyptohpis and Holoptychius 

 (Fig. 49). 



These are followed by the Rhizodontidce, represented by Tris- 

 tichopterus and Gyroptychius (Fig. 50) from the Old Red Sandstone, 

 and Rhizodus from the Lower Carboniferous of Scotland ; to these 

 succeed the Saurodipteridce, represented by Osteolepis (Fig. 51) and 



Fig. 53.— Tooth of Strepsodus. {See Table-case, No. 36.) 



Diplopterus, from the Old Red Sandstone ; and Megalichthys from 

 the Coal-measures. 



Strikingly remarkable in this case are the remains of Rhizodus 

 Hibberti, from Burdie House, the huge teeth and detached bones of 

 the head of which led the earlier observers to refer it to the 

 Labyrinthodonts ; Rhizodus was probably the largest of Palseozoic 

 fishes. 



Lastly, the Coelacanthidce, remarkable, as a family of fishes, for 



