Newman, Habits of Tortoises. 127 



less interesting psychologic data. Captivity inhibits normal 

 activity in nearly all tortoises; consequently I abandoned at an 

 early stage of my work the observation of specimens in confine- 

 ment and devoted myself to long-continued, and at times tedious, 

 observation of the various species as they live in their native 

 environment. 



Description of the Environment of Species Studied. — The work, 

 was done at Lake Maxinkuckee in northern Indiana. This lake 

 is nearly circular and measures 2.7 miles at its greatest diameter. 

 Its depth is on the average not great, at no point more than eighty- 

 four feet. The shores are low and, as a rule, slope gradually. 

 The bottom is for the most part muddy and rather soft except in 

 regions that are covered with stones. The water supply ot the 

 lake is mainly artesian and is very rich in all the mineral salts 

 necessary for animal and plant life. The lake bottom is almost 

 everywhere covered with a dense forest-like growth ot vegetation, 

 that affords a retreat for moUusca, Crustacea and fish of all sorts, 

 and a hunting and browsing ground for the various species of 

 tortoises. On the northeastern shore of the lake there are several 

 artificial lagoons that are freely connected with the main body of 

 water. These lagoons furnish unusual facilities for observation 

 as the water is always quiet. 



List of Species Studied and their Relative Abundance. — When I 

 first visited Lake Maxinkuckee in the fall of 1900, I was imme- 

 diately struck by the abundance and the variety of species of 

 tortoises there, but not until y/?arly two years afterward did I begin 

 a systematic study of their habits. 



The species that occur in the lake are as follows:^ 



1. Aspidonectes spinifer. 



2. Chelydra serpentina. 



3. Aromochelys odorata. 



4. Graptemys geographica. 



5. Chrysemys marginata. 



6. Nannemys guttata. 



7. Terrapene Carolina. 



The most characteristic and abundant species is Graptemys 

 geographica, outnumbering many times any other species found 

 in the lake." The other species occur in abundance in the follow- 



^The nomenclature and order is that found in Jordan's Manual of the Vertebrates. 



