The pale nuchal area was a cream-color, and the iris was grayish red.
"The Amphibians and Reptiles of Michoacán, México" by William E. Duellman
The Leydigian or nuchal organ is supposed to be auditory and to contain an otolith.
"Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 6" by Various
The mid-dorsal light line bifurcates either on the nuchals or on the parietals.
"Life History and Ecology of the Five-lined Skink, Eumeces fasciatus" by Henry S. Fitch
The marginal rim is widest at the posterior end of the carapace and lacking in the nuchal area.
"North American Recent Soft-shelled Turtles (Family Trionychidae)" by Robert G. Webb