712 



THE AMERICAN NATURALIST 



[Vol. XLII 



sume fresh. They will eat fish which have been recently 

 killed, in preference to partly decayed ones. 



In the spring, after moulting, there seems to be a con- 

 suming hunger. I have seen, at about 9 P. M., a craw- 

 fish within about six inches of the bank of a small pond, 

 so intent on pulling to pieces and devouring a partly de- 

 cayed fish, that he did not notice the very strong 

 acetylene light that I held close to him. 



Experiments with lights of various intensities, eluci- 

 dated the fact that crawfish are negatively phototactie to 

 strong light but positively phototactie to weak light. 



Eaw and cooked meat of all kinds, worms, dead fish, 

 pieces of clam, moulting crawfish, and dead crawfish were 

 eaten by the crawfish in confinement. They are said to 

 eat their own cast-off coats, but although these were left in 

 the aquarium for about a month, they were undisturbed. 



Tests were made to determine if the crawfish would 

 eat fish (trout), frog and toad eggs. Very few were 

 eaten, and these few when the crawfish had had nothing 

 to eat for ten days, and had nothing else to eat. 



Young frog and toad tadpoles were kept in the aquaria 

 and lived happily for a long time.. To determine if craw- 

 fish eat toad or frog tadpoles, twenty-five toad and frog 

 tadpoles were placed in a shallow dish, and, with a re- 

 newal of water every day, kept for four days with a 

 single, supposedly hungry, crawfish. Of the twenty-five 

 tadpoles, in all, but eight were eaten. 



About two weeks later, when the tadpoles had become 

 quite a little larger, a test was made with toad tadpoles. 

 A male crawfish was placed in a shallow aquarium jar 

 with twelve live tadpoles, and kept for three days, with 

 change of water twice a day. It was not until about fifty 

 hours had elapsed that he ate of the tadpoles, and then 

 he ate but one. 



A female crawfish was put into an aquarium jar at the 

 same time as the male, with 12 live toad tadpoles. This 

 was at 5 P. M. At 6 P. M., she had eaten all but one of 

 them. At 6 P. M., 17 more were put in, making 18 in all. 



