LIST OF HALF-TONES 



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I Figs. 1-3. The Spotted Salamander {Amhly stoma 



punctatum Linn): spherical eggs; full grown ^ 

 larva; spotted salamanders, i year old . " . 4 

 II "In May, when birch trees are in their splendour of 

 leaves, frogs and toads announce spring from all 

 the waterways" 5 



I I I Fig. 4. Diagrams showing location of lateral line sense 



organs in dorsal and side views of Bullfrog tadpole 6 



IV Figs. 5-6. Diagrams showing ventral views of shoul- 



der girdles and dorsal views of pelvic girdles . . 7 

 V Fig. 12. Explains fundamental structural character- \y 



istics mentioned in keys 42 



VI Figs. 13-16. ScaphiopMs holhrookii Harlan: skin of 

 side and upper arm; unbroken curve of jaws; black 

 horny thickening of first and second fingers . . 43 

 VII Figs. 17-19. Scaphiopus holbrookii Harlan: pro- 

 portions of body and leg; elevation of eye; webbed 



foot 56 



VIII Figs. 20-25. Scaphiopus couchii Baird: natural 



positions and structural characteristics . . 57 

 IX Figs. 26-30. Scaphiopus h.bombifrons Cope: vertical 

 pupil; shape of head; smooth skin; development 



of inner sole tubercle 62 



X The Toads in the pond. "May ist — ^The spreading 



leaves of the skunk cabbage and the unrolling 



fronds of the cinnamon fern" .... 63 



XI Fig. 32. Toads in artificial pond. Fig. 33. Toads' 



eggs laid June 12, 1903, and photographed 24 



hours later 66 



XII Fig. 34. Toads' eggs three days after laying. Fig. 

 35. Toad tadpoles hatched four days after eggs 



are laid 67 



XIII Fig. 36. Coiled mass of toads' eggs. Fig. 37. Black 



toad tadpoles 70 



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