FIG. 49 



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

 lache. X 5. 51. Pectoral fin of Acanthodian, /'ar^-.v^^j. (After SMITH WOODWARD.) 52. 

 Pectoral fin of Heptanchus. (After Gegenbaur.) 53. Pectoral fin of Xenacanthus 

 {Pleinacaiif/ms.) (After A. Fritsch.) 54. " Archipterygial" pectoral fin of Ceratodus. 

 (After Howes.) 



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



42 



