Motility of the turtle embryo, Chelydra serpentina (Linné).

Periodic motility of turtle embryos was observed during their incubation periods (60 +/- 5 days). Cyclic activity was first observed between days 10 to 14; it increased to a peak level of 50 percent of the standard observation period on day 30 +/- 5, then declined to low levels until hatching activities were initiated. During the first third of the incubation period, motility of the turtles closely resembled that previously described for chick embryos at similar stages of development.