Snapping Turtles
Box Turtles
Aquatic Turtles
Softshell Turtles
Sideneck Turtles
Sea Turtles
Tortoises

Good Reading: turtle head
Herpetological publication links (PDF):

Avise, et al. 1992. Mitochondrial DNA evolution at a turtle's pace... Mol. Biol. Evol. 9(3): 457-473.
Photo: Stock