428 



The Ohio Journal of Science [Vol. XIX, No. 8, 



quarrying operations. The thirty year pond is in the grounds of 

 the Soldiers' Home on the southern outskirts of Sandusky. 

 The two-year and the ten-year ponds are about half a mile 

 beyond this and within one hundred yards of each other. The 

 five-year pond is about five miles from Sandusky on Marble- 

 head peninsula and within one hundred yards of Lake Erie. 

 The fifteen-year pond is on Kelley's Island approximately 

 twelve miles from Sandusky and four miles off shore in Lake 

 Erie. The relative location of the series can be seen by referring 

 to the map of the region on this page. 



Ca&tfio. 





- ~~. Lake BuiE 



', Map of the Region. 



These ponds were under observation for four summers but 

 the detailed work on which this article is based was done during 

 the summers of 1916 and 1917. The seasonal succession is, 

 therefore, not considered. However, summer is the season 

 when in general the animals of a given habitat are most in evi- 

 4ence and the results given here are in all likelihood thoroughly 

 representative. 



In studying a given pond it was first examined as a whole 

 and then certain definitely delimited areas typical of its various 

 environments were studied intensively. In order to gain a con- 

 crete idea of the abundance of a given species all individuals taken 

 in certain small areas were counted. Because of difficulties with 



