Dorsal surface of snout lacking pale stripes just in front of eyes; pale postocular stripe having thick, black borders on adult males, but narrower, dusky or blackish borders on juveniles and large females; lower border of postocular stripe usually in contact with dusky postlabial line; no other markings on side of head; pattern on dorsal surface of soft parts of body of closely approximated, fine markings that are not in contrast with ground color, over-all coloration grayish; occasionally few larger and more contrasting markings, especially on hind limbs and anteriolateral surface of forelimbs. Underparts whitish, lacking markings, occasional black flecks or dusky marks posteriorly along ventral edge of carapace (TU 17306.3). Surface of carapace smooth in adult males; large females lacking prominences posteriorly in center of carapace or in nuchal region; anterior edge of carapace smooth in both sexes, but occasionally having regularly spaced furrows or wrinkles on hatchlings. _Comparisons._--_T. m. calvatus_ can be distinguished from _T. m. muticus_ by the absence of pale stripes on the snout just in front of the eyes, in having pale postocular stripes that have thick, black borders on adult males, and in having a juvenal pattern of large, circular spots that are often ocellate and three millimeters in diameter (no short lines). _Remarks._--I have not seen specimens of _calvatus_ from the Tombigbee-Alabama river drainage; presumably Cook's record (1946:185) from Lowndes County, Mississippi, represents this subspecies. It is still not certain that _calvatus_ occurs in streams that drain into Lake Pontchartrain, Louisiana; TU 17236 from the Amite River that lacks a diagnostic character is questionably referred to _calvatus_ (Webb, 1959:524). As mentioned previously _T. s. asper_ shows little evidence of intergradation with _T. spinifer_ in the Mississippi River drainage; _asper_ is present in streams of the Lake Pontchartrain drainage. _T. m. calvatus_ presumably shows a corresponding relationship with _T. m. muticus_ in the Mississippi River drainage. There are no specimens that indicate intergradation between _calvatus_ and _muticus_; _calvatus_ is expected in streams that drain into Lake Pontchartrain, Louisiana. Probably _calvatus_ occurs eastward in the Apalachicola drainage system. _Specimens examined._--Total, 38 as follows: FLORIDA: _Escambia_: KU 47116, 50852, 50854-55, 50835-36, TU 13473, 16682, 17301, 17302 (2), Escambia River, 2 mi. E, 1 mi. N Century. LOUISIANA: _East Baton Rouge_: TU 17236, Amite River, "near" Baton Rouge. _Washington_: TU 13795, Bogue Chitto River, Enon; TU 17303 (5), TU 17304 (4), Pearl River, "near" Varnado. _No data_: TU 17305.