carapacal laminae that are
pale with contrasting dark centers (at least on the lateral margins
of the carapace), intergular seam longer than interhumeral, obtuse
gular projections, and a relatively wider skull than other Mexican
representatives of the genus.

_Description of species._--Ground color of carapace pale yellow to
straw in smaller specimens, pale brown in larger specimens; in some
specimens a slight indication of darker radial markings on
carapace; epidermal areolae of carapace (if present) and first two
or three zones of growth (around areolae) dark brown to black,
their contrast with the ground color greater in smaller specimens;
ground color of lateral marginals yellowish, much paler than
remainder of carapace; black areolae of marginals contrasting
sharply with ground color even in old individuals; plastron pale,
approximately the same shade of yellow as lateral marginals, marked
with sharply contrasting blotches of black or dark brown in younger
specimens, becoming immaculate with age.

Carapace low, evenly arched or slightly flat-topped in cross
section, its height slightly more than 50 per cent of its length;
top of carapace, between highest parts of first and fourth central
laminae, more or less flat in profile; carapace flared, wider
posteriorly than anteriorly; central laminae all broader than long,
the first not (or but slightly) narrower posteriorly than
anteriorly; plastron deeply notched behind, the inner margins of
the notch straight, neither convex nor concave; gular projections
truncate (not pronglike) having no notch or but a shallow notch
between them; greatest combined width of gular laminae much greater
than greatest length; interlaminal length of gular greater than
that of humeral; one large axillary scute on each side,
approximately rectangular but slightly wider below than above; one
or two inguinal scutes on each side, the anterior roughly
triangular and much larger than posterior.

Anterior surface of antebrachium having enlarged, juxtaposed (or
slightly imbricated), osteodermal scales arranged in seven to eight
longitudinal rows, each scale yellowish with a black or dark brown
center; scales on lateral edge of antebrachium, from fifth claw to
elbow, ten in number and darker than other antebrachial scales; two
enlarged black-tipped, ye