32 



BERTRAM G. SMITH. 



IV. The Larva. 



A. Early Stages Studied in the Laboratory. 



The Neivly Hatched Larva. — At the time of hatching the larva 

 (see Fig. 9) retains a large yolk sac. The dorsal surface is well 



FlG. 9. Newly hatched larva of Cryptobranchus allegheniensis, 25 mm. long, 

 photographed while living. X 2 /^- 



pigmented, but the larva is pale as compared with amphibians 

 that live exposed to the light. The ventral surface is lacking in 

 pigment, leaving the abdominal region yellow from the presence 

 of yolk and the throat region white and nearly transparent. The 

 heart can be readily observed without dissection. The vitelline 



