surements (in millimeters) were made with a Vernier caliper and a
metal tape; those of the holotype were made to the nearest one-tenth
millimeter. Plastral length was measured from the posterior edge of the
plastron to the anteriormost edge of the ventral surface; other
measurements were maximal. Depth of shell was taken only on hatchlings
and an immature female. Hatchlings were arbitrarily designated as
specimens having plastrons shorter than 44 mm; sex of all specimens
except adult males was determined by dissection unless otherwise noted.

=Trionyx muticus calvatus= new subspecies

Gulf Coast Smooth Softshell

_Amyda mutica_ (in part), Stejneger, Bull. Mus. Comp. Zool.,
94(1):23-24, 1944.

_Amyda muticus_ (in part), Cook, Jour. Mississippi Acad.
Sci., 1941-1947, p. 185, 1946.

_Trionyx muticus_ Anderson, Copeia, 3:211, August 28, 1958.

_Holotype._--UI 31071, hatchling, sex undetermined, from the
Pearl River, Roses Bluff, 14 miles northeast Jackson, Rankin
County, Mississippi; obtained by William F. Childers on
August 25, 1952 (Plate 1).

_Paratypes._--A total of 20 alcoholic specimens: TU 17301,
hatchling male (Plate 2). TU 17302-.1, 16682, three
hatchling females, and TU 13473, adult female, from the
Escambia River, 2 miles east and 1 mile north of Century,
Escambia County, Florida; TU 17306, adult female, from the
Pearl River, 9 miles south of Monticello, Lawrence County,
Mississippi; USNM 7655, hatchling, sex undetermined, and KU
47117-19, three adult males, from the Pearl River, 1 mile
south to 4 miles north of Monticello, Lawrence County,
Mississippi; TU 17303-.4, 17304-.3, five hatchling males and
four hatchling females, from the Pearl River, Varnado,
Washington Parish, Louisiana; TU 17305, immature female, no
data.

_Diagnosis and definition._--A subspecies of softshell
turtle most closely allied to _Trionyx muticus muticus_ but
differing from that subspecies in having: (1) a juvenal
pattern of large, circular spots, (2) no stripes on dorsal
surface of snout, and (3) postocular stripe with thick,
black borders immediately behind eye in adult males. _T. m.
calvatus_ resembles _T. m. muticus_, and differs from the
several subspecies of _Trionyx spinifer_ in having: (1) no
enlarged tubercles on anterior edge of carapace, (2) no
ridge project