263 



Several empty nests were found in July, but some eggs, examined as late as Sep- 

 tember 1, contained young which would have been ready to hatch about a month 

 later. The number of eggs found in several nests was as follows: 9; 12; 17; 18; 

 27; 32. 



Aroiiiochelys odorata Bosc. This species is abundant, but not conspicuous. 

 Individuals were oftenest seen the latter part of June and first part of July while 

 laying their eggs. The eggs are laid in the rotten wood in the tops of stumps 

 standing in the margin of the lake. The turtles were frequently found in the 

 tops of these stumps, and some of their eggs wedged as far into the rotten wood 

 as a finger could bore. Rotten logs removed some distance from the water are 

 also favorable places for egg laying, and in a mucky place of small area at the 

 edge of the lake 362 eggs were taken at one time. The number of eggs laid by 

 one individual varies from 4 to 7, this number being usually in a cluster. At this 

 rate about sixty turtles must have contributed to the nest of 362. While passing 

 along a wheat field some turtles were seen coming from it, and on inspection it 

 was found that they had deposited their eggs in the ground in depressions made 

 by a cow while walking over the ground when it was soft. Still other eggs were 

 found in bundles of rushes drifted together. An interesting change of habit 

 seems to have taken place among these turtles during the last fifty years. Before 

 that time the number of stumps standing in the margin of the lake must have 

 been exceedingly small. The present large number is due to the rising of the 

 lake after the building of the dam and the subsequent cutting down of the trees 

 whose boles had become submei'ged. The habit of laying eggs in stumps can not 

 be of much more than fifty years' duration. 



The time of laying must l)e scattered over considerable time, for many eggs 

 were found hatched in August, while some obtained about then hatched at 

 various times from September 15 to November 1. These were, however, kept in 

 a box in a room and therefore removed from normal conditions. The age of this, 

 as of all other hard-shelled turtles, can be estimated by the lines of growth on 

 the horny cuticle. The originally exposed part of the plate occupies the medio- 

 cephalic corner of the plate and additions occur as smooth strips along the outer 

 and posterior margins. The strips are quite distinct in early years, but become 

 more or less obscure with age. 



Chri/Aeiiii/.^ marffinata Agassiz. This appears to be the most abundant turtle of 

 the lake. How far its apparent abundance may be due to its habits I am unable to 

 say. It is found floating or (juietly paddling along, its head out of the water, but 

 on nearer approach it always turns tail and seeks refuge in the abundant chara 

 fields or in other hiding places. The chara fields are traversed ))y narrow paths 



