No constant differences in the muscles or nerves was found between _T. cupido pinnatus_ and _T. cupido attwateri_. Only one constant difference was found between _T. cupido_ and _T. pallidicinctus_: a thicker fleshy origin of M. extensor iliotibialis lateralis in _T. cupido_ (associated with a thicker edge of the lateral iliac process). Although no constant differences in the nerves were found between _Pedioecetes_ and _Tympanuchus_ (both species), 17 constant differences in the muscles were found between these two genera. Seven of these differences pertain to features of a single muscle--M. flexor cruris medialis. Compared with the condition in _Tympanuchus_, M. flexor cruris medialis in _Pedioecetes_ has a wider origin, a partly fleshy (instead of entirely tendinous) origin, a more pronounced curvature of the line of origin, a wider insertion, an insertion posterior (rather than anterior) to the medial collateral ligament, an insertion that attaches in part to the articular capsule, and a shorter tendon of insertion (resulting in the fusion of the common insertional tendon of Mm. flexor cruris lateralis and femorocruralis with the fleshy belly rather than with the insertional tendon). Other differences include the following. A more extensive posteroproximal aponeurosis of M. extensor iliotibialis lateralis in _Pedioecetes_ (resulting in a narrower fleshy origin); a more nearly straight line of origin of this muscle (associated with a less pronounced lateral iliac process); a thinner fleshy origin of this muscle (associated with a thinner edge of the lateral iliac process); a wider M. flexor cruris lateralis that is fleshy up to the origin from the vertebrae; a wider fleshy origin of M. iliacus; the origin of M. caudofemoralis pars iliofemoralis not reaching the ventral edge of the ischium; a narrower origin of M. adductor superficialis; a wider M. femorocruralis; and a shorter belly of M. extensor digitorum longus. Some additional differences between these two genera, which are slight in degree, are given in the accounts of the muscles. If additional specimens were studied, some of the differences listed above possibly would prove to be subject to individual variation and so could not properly be listed as constant differences between the two genera.