FIG. 20. Development of the hind foot of a 

 salamander, Triton t&niatus. After Strasser, 

 from Lull's Organic evolution, published by 

 the Macmillan Company. 



FIG. 21. Foot of a reptile, Ranodon 

 sibericus: f, fibula; h y femur; /, 

 tibia; I, II, III, IV, V, digits 1-5. 

 After Wiedersheim, from Lull's 

 Organic evolution, published by the 

 Macmillan Company. 



