_spinifer_, _hartwegi_ and _asper_ but differs from _guadalupensis_ and _emoryi_ in having tubercles along the anterior edge of the carapace that are conical having sharp tips in males, and conical in large females. _T. s. pallidus_ resembles _spinifer_ and _hartwegi_ but differs from the other subspecies in having a narrow head. _T. s. pallidus_ differs from _emoryi_ but resembles the other subspecies in having a wider carapace. _T. s. pallidus_ resembles _emoryi_ and _guadalupensis_, and differs from the other subspecies in having the carapace widest farther posterior than one-half the length of the carapace. The snout of _pallidus_ and _guadalupensis_ is shorter than in _spinifer_ and _hartwegi_, but longer than in _emoryi_. _T. s. pallidus_ differs from _asper_ but resembles the other subspecies in having a relatively long plastron. _Remarks._--Intergradation of the subspecies _pallidus_ and _guadalupensis_ is of a clinal nature in which populations successively show a gradual resemblance to _guadalupensis_ from western Louisiana and eastern Texas westward to central Texas. Because the sharpest break in this cline of characters occurs between the Colorado and Brazos River drainages, the turtles living in the Brazos River drainage and eastward are referred to _pallidus_, whereas those in the Colorado River drainage and westward are referred to _guadalupensis_. For further comments on intergradation between these two subspecies, see the account of _T. s. guadalupensis_. Taylor (1935:217-18) reported on some specimens of _Amyda spinifera_ that were obtained by Mr. R. E. McEntyre in "... the spring and summer of 1926, chiefly about Lewisville, Lafayette County (Arkansas)." Of the catalog numbers listed by Taylor from Lewisville, 58 (KU, alcoholic) represent _pallidus_. Three, having the same locality data, have features that are characteristic of _hartwegi_. KU 2944 (one of three specimens having this catalog number) is a female having a pale, mottled and blotched carapace approximately one foot in length; there are remnants of two dark ocelli, and many widely-scattered, well-defined dark spots near the periphery of the carapace. KU 2963 (one of three specimens having this catalog number) is an adult male that has solid, blackish dots on the entire surface of the carapace. KU 2964 (one of two specimens with this catalog number) is an adult male that has ocelli approximately five millimeters in diameter on the carapace (indistinct in center of carapace).