No. 635] SHORTER ARTICLES AND DISCUSSION 557 



for food available in fresh water ; greater metabolic activity due 

 to gonad development which demands a greater oxygen supply. 



3. Summer activities consist in spawning, feeding, lazy move- 

 ments from the marshes to the brackish water and back again. 



4. In the autumn, migration is less constant and the larger 

 fish are less numerous. 



5. In the winter, migration ceases entirely as the marsh pools 

 are scumming with ice. Some landlocked individuals burrow 

 into the mud of permanent pools, coming out occasionally as the 

 sun warms the water. Many fish are killed by the cold as they 

 remain in temporary pools with bottoms composed of caked mud 

 and grass offering no shelter. 



6. The majority of Fundulus heteroclitus return to salt water 

 in the winter, probably remaining near the mouths of rivers 

 until spring. 



F. E. Chidester 



BIBLIOGRAPHY 



