U. S. B. F. — Doc. 



Plate XXI. 



I iCo. 1 :o 3,— TRANSFORMATION SIZES. NATURAL SIZES. 



1, Bullfrog; 2, green frog; 3. pickerel froe; 4. leopard frog; 5, tree toad; 6, wood frog 

 7, peeper; 8, common toad. (After Wright, Carnegie Publ. No. 197.) 



