552 



THE AMEBIC AN NATURALIST 



[Vol. LIV 



ated as temporary. The bottoms of the permanent pools were 

 covered with soft mud and strewn with sedge and eel grass fre- 

 quently dispersed in windrows as a result of repeated wave 

 action. The bottoms of the temporary pools were covered with 

 matted grass bound together by hardened clay. 



At the Bonhamtown marshes near New Brunswick, intensive 

 study was made of three large permanent pools, one of which 

 was partially drained by a ditch connecting it with the Raritan 

 River. Additional studies were made of conditions in many 

 other permanent pools, temporary pools and ditches. 



The three permanent pools studied most intensively were quite 

 different in their character. The largest one was about 40 feet 

 long and ranged from a foot to 10 feet in width, but its depth 

 varied considerably with the tides. At its larger end it was 

 connected with the Raritan River by means of a long narrow 

 drainage ditch. The second was an almost circular pool about 

 25 feet in diameter and in no place more than 18 inches deep ; 

 much of the time it was only about 6 inches deep. The third 

 pool was about 30 feet long and about 10 feet wide. At one 

 end it was 20 inches in depth and at the other about 12 inches. 



Collections were made by means of a 20-foot minnow seine and 

 several small dip nets. Fish were frequently preserved in weak 

 formalin in the field when it was desired to examine their stom- 

 achs at leisure. Usually, however, they were brought to the 

 laboratory and examined freshly killed or else liberated in 

 aquaria. 



Records of temperature, salinity and specific gravity were 

 taken with each collection, while the height of the tidal flow and 

 the depth of the pools were approximately recorded. 



Spring Migration 



Fundulus keteroclitxfs begins fts migration from the mouth of the 

 Raritan River up beyond the salt water to the slightly brackish 



