Minor differences in muscle pattern, like those already mentioned, are consistent also between subfamilies, but correlation of these minor differences with function is difficult. There is the implication, however, that in all the groups except the carduelines and ploceids, the emphasis is on greater strength and mobility of the leg. In the carduelines that were studied the origin of the _m. sartorius_ does not extend so far craniad as in the other species. In the latter, at least half of the origin is from the last one or two free dorsal vertebrae; in the carduelines no more than one third of the origin is anterior to the ilium. It is conceivable that the more craniad the origin, the stronger the forward movement of the thigh would be. In _Passer_, _Estrilda_ and _Poephila_, and in all the cardueline finches examined, the bellies of the _m. flexor perforans et perforatus digiti II_ and the _m. flexor perforans et perforatus digiti III_ are more intimately connected than they are in the other species studied. Thus, the amount of independent action of these muscles in _Passer_, in the estrildines, and in the carduelines probably is reduced. In _Passer_, the estrildines, and the carduelines the edges of the sheathlike tendon of insertion of the _m. perforatus digiti III_ are thickened; as a result the insertion appears superficially to be double but closer examination reveals that there is a fascia stretched between the thickened edges. In the other species examined, the insertion is sheathlike throughout and there are no thick areas. I cannot explain this on the basis of function. The difference, however, is obvious and constant. Aside from the differences noted above, there were variations of muscle pattern that seem to be significant only in _Vireo olivaceus_. In this species the central, aponeurotic portion of the _m. iliotibialis_ is absent. The origin of the _m. adductor longus et brevis_ is from the dorsal edge of the ischiopubic fenestra and not from the membrane covering this fenestra. The origin of the _pars posticus_ of this muscle, furthermore, is fleshy and not tendinous as it is in the other species. The _m. flexor perforatus digiti II_ is larger and more deeply situated in _Vireo_ and has, furthermore, no connection with the _m. flexor hallucis longus_. The latter muscle is smaller and weaker than in any of the other species and has only one (the posterior) head of origin. The _m. flexor hallucis brevis_, on the contrary, is larger than in the other birds, compensating, probably, for the small _m. flexor hallucis longus_. In those differences, however, which separate the carduelines and ploceids from the other birds studied, _Vireo_ resembles, in every instance, the richmondenines, emberizines, tanagers, warblers, and blackbirds.