352 BOTANICAL GAZETTE [NOVEMBER 



occupying areas of an acre (half a hectare) or more, but there are 

 several of considerable size. Portage and Whitmore 1 Lakes occupy 

 one and one-fourth to one and one-half square miles (325-390 hec- 

 tares), while Union, Straits, Four-Mile, Ore, Independence, etc. 



FIG. i. Map of the Huron drainage basin. The boundaries of the interlobate 

 moraine are shown by the lines . The boundary between the clay morainic 

 belt and the lake plain is marked by the line . 



cover a fourth to half a square mile (65-130 hectares). A very large 

 percentage of the tributaries lie in flat-bottomed depressions whose 

 surface approximates the ground-water level, consequently producing 

 thousands of acres of swamp and marsh land. Everywhere occur 

 small undrained depressions, some well above the average ground - 

 water level, others containing lakes and bogs. It is also worthy of 



1 Not connected with the Huron River by surface drainage. 



