_ornata_, and _taylori_) and to three (_elegans_,
_gaigeae_, and _taylori_) the number known in Coahuila. My own
studies of these six subspecies indicate that they are, beyond
reasonable doubt, members of a single polytypic species (_scripta_).
I tentatively follow Williams (1956:153) in rejecting "_cataspila_"
as an invalid name.

Three specimens of _Pseudemys scripta_ obtained by Robert G. Webb in
the Rio Chiquito at a point 8 mi. W of Nadadores, 2100 ft., where the
river flows out of the basin of Cuatro Cienegas, have many
characteristics in common with _taylori_, but resemble _elegans_
closely in several characters as follows: no extensive melanism;
plastral markings tending to be brownish; anterior plastral markings
smudgelike, isolated or nearly isolated; markings on lateral scutes
tending to have vertical, linear arrangement; cutting edge of mandible
weakly serrate; femoral edges of plastron not reflected ventrally; one
or more fine, pale lines between two major stripes on antebrachium;
gular longer than pectoral in one specimen, longer than femoral in
both specimens. The nature of these specimens suggests that parts of
the Rio Salado drainage north and east of Cuatro Cienegas are in a
zone of intergradation between _taylori_ and _elegans_. I have
examined what I consider to be typical examples of _P. s._ _elegans_
from the region of Muzquiz (CNHM 28843-45, 55625-45), and from Don
Martin Reservoir (KU 33524). These localities are, respectively,
approximately 70 miles north-northeast and 100 miles east-northeast of
Cuatro Cienegas. The specimens from Muzquiz are presumably the same
that Carr (1952:262) treated as "... _elegans-cataspila_ intergrades,
but with a strong leaning toward eastern _elegans_...." Populations of
_P. scripta_ in central eastern Coahuila (between the above-mentioned
localities and Cuatro Cienegas) probably are a conglomerate of only
two subspecies (_elegans_ and _taylori_), not including _gaigeae_ (as
was suggested by Hamilton, 1947:65 and by Carr, op. cit.:241, map
17;262).

Specimens reported by Schmidt and Owens (1944:101) as _P. s. gaigeae_
(from several localities in the region mentioned above) have been
examined in the course of my study and prove to be _P. floridana
texana_. A specimen reported by Shannon and Smith (1949:399; IU 4094,
Hidalgo Co., Texas) as being either _gaigeae_ or an _elegans-gaigeae_
intergrade, has been examined and is here regarded as a typical
specimen of _e