The translation or conversion of shape into quantitative terms so that different shapes can be compared and interpreted is a profound problem in Systematic Biology. The research will provide information on the application of the fitting techniques that will be of use to researchers in many areas of biology and on the nature of shape variation of importance to those interested in ecological and evolutionary questions concerning turtles. The proposed research has two main goals. The first is to compare existing and newly developed rotational fitting methods using a set of three- dimensional landmark locations from biological material. The data will consist of the coordinate locations of biologically and geometrically defined landmarks on the carapace of the yellow- bellied turtle. Trachemys scripta scripta. The second goal is to use this data to investigate shape differences resulting from sexual dimorphism, habitat-related growth differences, and geographic variation within this subspecies.