FIG. 49 



Figs. 49-54. — Evolution of paired fins. 49-50. Pectoral and ventral fins of Cladose- 

 lache. X s. 51. Pectoral fin of Acanthodian, /'a^vx?^^. (After SMITH WOODWARD.) 52. 

 Pectoral fin of Heptanckus. (After Gegenkaur.) 53. Pectoral fin of Xenacanihus 

 {Plei/raamtkus.) (After A. Fritscu.) 54. " Archipterygial " pectoral fin of Ceratodus. 

 (After Howes.) 



B. Basal. D. Dermal. R. Radial. 



42 



