66 BERTRAai G. SMITH 



carried on during the present year, I am profoundly indebted for 

 his constant encouragement, kindly criticism, and valuable advice; 

 for this I desire to record my grateful appreciation. 



II. THE ADULTS 

 A. HABITAT 



Cryptobranchus allegheniensis was found abundantly in the 

 Brokenstraw Creek, a tributary to the Allegheny River, in north- 

 western Pennsylvania. The most favorable locality extends 

 from the confluence with the Allegheny five or six miles up- 

 stream. The stream has a rather rapid descent, and a gravelly 

 or rocky bottom. Shallow and rocky rapids make up the greater 

 part of its course, alternating with areas of deeper and more quiet 

 water. 



As a rule, Cryptobranchus is found more abundantly in rather 

 shallow and rapid water, where large flat rocks afford suitable 

 cover. Usually the animals lie concealed in cavities under these 

 rocks. As more than one individual is seldom found under a 

 single rock, we conclude that its life is in general a solitary one. 

 Cryptobranchus rarely comes out of its hiding place in the day- 

 time, except in the spring and early summer and during the breed- 

 ing season (the first two weeks of September). At night they 

 venture abroad in large numbers ; they are then seen by fishermen 

 spearing by torchlight, who commonly report them in the deeper 

 and more quiet water. 



The cavity or cavern used for a more or less permanent dwelling- 

 place has a rock for its roof and the gravelly bed of the stream for 

 its floor. In perhaps the majority of cases, ready-made cavities 

 are chosen as homes, and these are reached by a natural opening. 

 But the cavity sometimes bears evidence of having been in part 

 hollowed out by the animal, and is occasionally reached by a single 

 tunnel-like entrance on the down-stream side of the rock; this is 

 more often the case in cavities used for spawning purposes. 



There is a striking similarity between the habitat of Crypto- 

 branchus allegheniensis and that of the 'giant salmander' of 

 Japan as described and figured by Ishikawa ('04). 



