Proceedings of Sixth Annual Meeting 73 



acres in extent. It is an open field swamp, and while only seen 

 from the train, did not appear difficult to drain by ditching. 



In the vicinity of Gibbstown (5 miles distant from Hog Island 

 and 10 miles from Gloucester) occurs the largest single area of 

 marsh in either Camden or Gloucester counties. It is likewise the 

 one where the most extensive breeding probably occurs, and will 

 be the most difficult to drain. There can scarcely be less than 2000 

 acres of swamp here. The marshy area is larger than appears on the 

 map, for there is much swamp in the Thomson Point neighbor- 

 hood, which is dry according to the Geological Survey Map. 



This Gibbstown swamp consists for the most part of open tus- 

 sock and cattail. It is traversed or drained by Repaupo Creek, 

 the Sand Ditch, Pargey, London, Still, and Nehonsey Brooks, and 

 numerous ditches. This drainage system discharges eventually by 

 sluices and tide-gates under the Delaware River dikes. Most of 

 this area lies very low and to drain it sufficiently to stop mosquito 

 breeding would doubtless require pumping. Mr. Thomas, Chief 

 of Safety and Sanitation for the Gibbstown plant of the Dupont 

 Powder Company, who went over with the speaker, the part of 

 this area (about l^OO acres) belonging to the latter company, is 

 authority for the statement that it is impossible to drain the Thom- 

 son Point property by gravity. 



The 140 acres of marshy foreshore outside the dike east of 

 Thomson Point indicated on the map, is nearly all flushed by the 

 tide. Breeding could only occur in pockets among some timber 

 at one or two places. 



Chester and Monds Islands lie in the Delaware between Chester, 

 Pennsylvania, and the Thomson Point or Gibbstown property of 

 the Dupont DeNemours Powder Company, in Gloucester County, 

 New Jersey. They are about 4^ miles distant from Hog Island. 

 Each island is a huge cattail swamp. On Chester Island there are 

 340 acres of this character, and on Monds Island, 280 acres. About 

 one-third of Monds Island and one-fourth of Chester Island were 

 formerly enclosed by banks and drained. The old dikes, however, 

 have disintegrated to such an extent that in some places they can 

 no longer be traced. The area behind the lines of the old dikes 

 is now no different from the land outside. The old drainage ditches, 

 too, have largely or w^holly disappeared. The surface soil on these 

 islands is a soft brown muck, consisting chiefly of organic matter. 



