. The Canadian field-naturalist. 70 The Canadian Field-Naturalist Vol. 77 TEMPERATURE ( °F). Figure 1. Early morning (0800 hrs) and late afternoon (1700 hrs) soil temperature pro- files at Fredericton, New Brunswick, based on monthly means from 1959 to 1962. Turtle nests would be subjected to the environmental conditions of the 10 cm level. °F and °F lower under the screening. There is, however, the possibi- lity of the "greenhouse effect" here, where heat loss at night is lessened by the presence of the screen cover. A constant temperature recording apparatus might even show
. The Canadian field-naturalist. 70 The Canadian Field-Naturalist Vol. 77 TEMPERATURE ( °F). Figure 1. Early morning (0800 hrs) and late afternoon (1700 hrs) soil temperature pro- files at Fredericton, New Brunswick, based on monthly means from 1959 to 1962. Turtle nests would be subjected to the environmental conditions of the 10 cm level. °F and °F lower under the screening. There is, however, the possibi- lity of the "greenhouse effect" here, where heat loss at night is lessened by the presence of the screen cover. A constant temperature recording apparatus might even show that although less heat was gained during the day under the screen, there was less heat lost at night, so that the total energy gain may be the same over a twenty-four period or the "greenhouse effect" might actually raise the mean temperature of the soil above normal and thus hasten incubation. The screening and the circle of rocks at the Emydoidea nest would have considerable effect as wind shield and thus lessen evaporation and cooling. In addition, the angular surfaces of the rocks could reflect additional heat onto the ground and into the air above the nest. Hatchlings A Chrysemys was observed on the night of July 3, 1959, laying eggs only eight feet from the screened over Emydoidea nest and next morning the area was covered with screening. Both nests were kept under observation and on September 27 the Emydoidea hatchlings emerged, after a period of 88 days. This is the first time an incubation period has been reported for this species. Hatchlings have previously been found in September by Conant (1938) and Sexton (1957). The Chrysemys hatchlings first appeared on April 7, 1960, when three dug out to the surface after a period of 277 days. There had been snow over the nest the previous week, the adjacent Grafton Lake was ice-free only at the margins and this was freezing over each night, and wood frogs, Rana sylvatica, and spring peepers, Hyla crucifer, were
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