he subspecies of T. spinifer (Conant and Goin, 1948), and that the degree of difference between calvatus and muticus is greater than that between some subspecies of T. spinifer.
Specimens examined.--All the localities listed below are plotted on the distribution map (Fig. 1). Only those specimens of T. muticus muticus are listed that serve to delimit the range of T. m. calvatus. Fortunately, the identification of the specimens of muticus is certain as all show the characteristic juvenile pattern, except the large female, TU 7543, from southeastern Louisiana. USNM 95133-34 (carapaces and plastrons only) and TU 17236 are females, which lack the diagnostic spotted pattern of calvatus; the former are referred to this subspecies on geographic grounds (Pearl River at Columbia, Mississippi). TU 17236, from the Amite River, is dubiously relegated to calvatus on the supposition that this river and others in the Lake Poncha