HABITS OF CRYPTOBRANCHUS ALLEGHENIENSIS. 



17 



The absence of black pigment in the eggs is probably corre- 

 lated with the fact that they are laid in darkness. The eggs of 

 Neelurus, which are also laid under cover, are likewise devoid of 

 pigment- 



During the breeding season the water is unusually low. In 

 one case a nest was found at the extreme water's edge, so that 



Fig. 5. Unfertilized eggs of Cryptobranchus allegkenie?tsis, after two days' im- 

 mersion in water. Natural size. 



the eggs were barely immersed, yet most of them were develop- 

 ing. In this way, by the periodical drying up of the water in 

 swamps, may have originated the terrestrial nesting habits of 

 Amphiuma, described by Hay ('88). 



Fertilization. — In a previous paper ('06 2 ), the conclusion was 

 reached that fertilization in Cryptobranchus is internal. The evi- 



