Immature female (1 specimen). Carapace circular having juvenal pattern of large spots, some of which have borders darker than their centers and are best described as ocelli; junction of pale margin and ground color of carapace formed by ill-defined, ragged dark border; dorsal surface of forelimbs and hind limbs finely streaked and dotted, larger marks occurring toward insertions of forelimbs; lower border of pale postocular stripe in contact with upper margin of postlabial pale stripe; no stripes on dorsal surface of snout; fine markings on dorsal surface of neck. Maximal measurements are: length of plastron, 56 mm; length of carapace, 82 mm; width of carapace, 77 mm; depth of shell, 13 mm; width of head, 12 mm.
Adult males (3 specimens). No striping on dorsal surface of snout; pale postocular stripe with thick, black borders immediately behind eye; width of black borders equal to approximately one-half width of pale postocular stripe; dorsal surface of soft parts of body with indistinct markings that are larger on hind limbs; plastron and ventral surface of soft parts of body without markings; small dark spots posteriorly along ventral edge of carapace; pale margin of carapace lacking markings or having few small black spots; carapace circular with or without pattern of large spots. Maximal measurements of smallest and largest specimens, respectively, are: length of plastron, 108 and 118 mm; length of carapace, 160 and 177 mm; width of carapace, 142 and 152 mm; width of head, 21 mm.
Hatchlings (14 specimens). These paratypes resemble the holotype in all features mentioned; markings on neck tend to form longitudinal streaks in TU 17303 and 17304. There are no secondary sexual differences in hatchling turtles.
There is some variation in hatchling turtles. Four from the Escambia River have dorsal spots 3 mm or larger in greatest diameter and on three specimens the dorsal spots number 27, 37 and 37 (total number not discernable in TU 16682); none of the dorsal spots is ocellate. Maximal measurements of these three hatchlings, respectively, are: length of plastron, 35, 36 and 37 mm; length of carapace, 50, 50 and 52 mm; width of carapace, 44, 45 and 47 mm; depth of shell, 11 mm; width of head, 9 mm. Nine hatchlings from the Pearl River at Varnado have more (all small) dorsal spots, which may be ocellate. The dorsal spots and ocelli do not exceed 2 mm in their greatest diameter except that some of those of TU 17304 are 3 mm; the spots range in number from 38 (TU 17303) to 63 (TU 17304). Maximal measurements of the smallest and largest specimens, holotype excepted, are: length of plastron, 30 and 33 mm; length of carapace, 42 and 46 mm; width of carapace, 37 and 43 mm; depth of shell, 9 and 10 mm; width of head, 9 and 10 mm. The holotype resembles hatchlings from the Escambia River in having large, non-ocellate dorsal spots 3 mm in greatest diameter, and larger measurements.
One other specimen (not designated as a paratype), consisting of a head with a few attached cervical vertebrae, was obtained on a sand bank of the Escambia River, Florida. The postocular stripe, bright yellow with black borders, was especially vivid in this adult male (KU 47116).
Fig. 1. Map of southeastern United States showing record stations of Trionyx muticus calvatus (solid symbols) and Trionyx m. muticus (open symbols). Circles indicate specimens examined; triangles indicate records in the literature. The question mark refers to a specimen bearing catalogue number 17236 in the collection of Tulane University (see comments on page [524] concerning No. 17236 from the Amite River).
Range.—Trionyx m. calvatus is known from the Pearl, Pascagoula and Escambia river drainages and is to be expected in the Tombigbee-Alabama river drainage ([Fig. 1]). Tinkle (1958:41, fig. 53, stippled) has indicated the probable range of calvatus. This subspecies is unknown from the Mississippi and Tennessee river drainages, which are inhabited by T. m. muticus. The western limit of distribution is the Pearl River drainage and probably those streams of the Florida Parishes of Louisiana that drain into Lake Ponchartrain. The most easterly record of occurrence for T. m. calvatus is in the Escambia River drainage; the eastern extent of geographic range is not known.
I have seen three preserved young turtles having the characteristic spotted pattern from the Pascagoula drainage in eastern Mississippi. These specimens are uncatalogued and in the collections at Mississippi Southern College, Hattiesburg, Mississippi.