76 /. H. Pozvcrs 



Fig. 3. Long, depressed head, with great gape of mouth, resulting from 

 cannibalism, followed by long starvation in larva. ' Length of entire speci- 

 men (in formalin), 23.3 cm. 



Fig. 4. Very short, high-arched head of adult 23.2 cm. long. 



Fig. 5. Head of larva of corresponding type, 25.4 cm. long. 



Plate IV 



Fig. 1. Dorsal view of slender adult (formalin preservation) resulting 

 from slow growth and free-swimming habit of larva. Length of specimen 

 in life 19.7 cm. 



Fig. 2. Dorsal view of adult resulting from larva on pi. II, fig. 2. 



Fig. 3. Dorsal view of adult modified by continuous high feeding in 

 water. 



Fig. 4. Head showing exceptionally pointed muzzle. Result of excessive 

 free-swimming life and daphnid feeding. 



Fig. 5. Head normal, of wild adult. 

 ■ Fig. 6. Posterior foot of slender adult nearly 19 cm. in length, result of 

 rather slow growth. 



Fig. 7. Posterior foot, with very slender toes, of 21 cm. adult, result of 

 growth and metamorphosis at low temperature. 



Fig. 8. Posterior foot of a robust, 19 cm. adult. Toes rendered slender 

 by same process as with fig. 7. 



Fig. 9. Posterior limb and foot of rapidly grown animal 20 cm. long. 



Fig. 10. Posterior limbs and feet of a very slender adult male, 28 cm. 

 long. 



Plate V 



Fig. 1. Adult female showing broad, thick tail due to heavy feeding in 

 water. 



Fig. 2. Adult male showing broad, thin, and elongated tail due to slow 

 growth of larva, aquatic life, and sexual maturity of adult. Formalin. 



Fig. 3. Slender adult, originally with slender tail, which latter finally 

 expanded as result of heavy feeding in water. 



Fig. 4. Anterior portion of robust adult showing depression of head after 

 long life in water. 



Fig. 5. Head of same animal as fig. 8. Shows extremely truncated muz- 

 zle acquired during larval life and accentuated by aquatic life of adult. 



Fig. 6. Head of same animal as fig. 2, though photographed at an ear- 

 lier age. Shows the broadening of the head due to aquatic life of adult 

 despite extremely slender body and tail. 



Fig. 7. Posterior limbs and feet of same animal as fig. 2, though pho- 

 tographed at an earlier age. Toes small and narrow as result of aquatic 

 life. 



Fig. 8. Posterior limbs (very typical) of another adult kept long in 

 water; toes have become narrow and cylindrical. 



272 



