Page:Popular Science Monthly Volume 38.djvu/74

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64
THE POPULAR SCIENCE MONTHLY.

always lay at night, and deposit all their eggs in a single nest. As soon as the sun goes down the female sets about her maternal duties. She wanders over the fields with restless activity until she finds a locality suitable for the formation of the nest. Stubble-fields, or those which, having been recently under cultivation, are covered with a thin growth of grass, are preferred. She then begins to scratch up the earth with her hind feet, using first one

PSM V38 D074 Old male turtles fighting.jpg

Fig. 3. — Old Males fighting. Showing extreme variation in the coloring of the species. (From a sketch made at the time.)

and then the other. After about three hours of patient labor, a small hole about four inches in depth and two inches in diameter, a little wider at the bottom than at the top, has been excavated. An egg is then dropped into the cavity and carefully pushed against the side by the hind foot of the mother; another is then laid and placed in position as before, until from four to six eggs are ranged side by side in the bottom of the nest. The earth is then carefully scraped back by the hind feet, and finally the grass and leaves are scratched over the opening and pressed down so skillfully that the ground appears as though it had never been broken. By this time it is past midnight It is remarkable that the females do not seem to fear the presence of the observer, but continue their labors, although he may be but a foot or two away. When once started digging the nest they rarely abandon the work. We have observed a tortoise of another species (Nanemys guttata) which dug all night, and finally completed its nest on the noon of the day following.

The eggs are covered with a soft white calcareous shell. They