1922] Phases in the Development of Ciirysemys Cinerea 55 



were found in oviposition later than June 25th, but as late as July 

 7th turtles bearing fully formed eggs were found crushed upon the 

 road as they were seeking high ground for laying. This latest ob- 

 servation was made by Dr. E. M. Gilbert, but similar previous cases 

 were observed by the writer as late as July 1. The latest date previ- 

 ously reported for these turtles with eggs is July 1, when Ruthven 

 (1910) collected a turtle with ten eggs in the oviduct. 



The eggs are usually deposited during the afternoon or evening. 

 One turtle was found packing the hole of the nest at 4 :00 p. m., which 

 indicates that the work of nest building was begun before noon. 

 None were found in oviposition in the morning but a number were 

 taken at 4 :30 p. m., and a few were just beginning the work of nest 

 building as late as 6 :00 p. m. 



These turtles select high ground in which to build their nests. 

 Sometimes this is a considerable distance from the water or, where 

 the banks are high, it may be only the distance of a few feet. Usually 

 the ground chosen is hard and dry but a sandy beach may be used. 

 The dirt is first moistened with water from the supernumerary bladder. 

 *This is shown by the fact that the dirt in the hole and surrounding 

 it closely is moist while that farther away is hard and dry. The 

 moistened dirt is worked up and thrown out by the hind feet. It 

 was impossible to determine whether or not the tail was used in dig- 

 ging the hole, as some investigators have reported, since it was al- 

 ways either in the hole or turned up under the plastron while the 

 work was being done. When the hole has reached a depth of from 

 three to four inches a small cave-like excavation is made at one side 

 into which the eggs are dropped without any reference to position. 

 They frequently are found standing on end but more often they 

 are lying on one side. After the last egg has been deposited the 

 dirt is pushed loosely around them and the neck of the nest is packed 

 with wet dirt which is tamped down with the plastron. The nest 

 is then scratched over and is made to resemble the surrounding 



* It was considered desirable to determine whether the great quantity of water found in 

 the supernumerary bladder was water removed from the circulation stream or drawn in 

 through the cloaca, since the quantity of liquid in the supernumerary bladder increases 

 markedly during the laying season and decreases after the laying season is past. While the 

 evidence on this point is incomplete, it is thought host to present it at this time. The urine 

 from five turtles was centrifuged and microscopically examined, and since neither diatoms, 

 green algae or protozoa were found, it is doubtful" if this is other than excreted water. 

 Chemical examinations were made to determine the percentage of nitrogen compounds in 

 the urine. It was found, in the summer, to be .00055%. Materials for fall determination 

 were lost in transit. 



