(Hirundinidae; Ϯ Blue-and-white Swallow P. cyanoleuca) Gr. πυγη pugē rump; χελιδων khelidōn, χελιδονος khelidonos swallow; "[Synopsis] Basal joint only of middle toe adherent externally, and free at extreme end. Tibial joint covered with feathers which extend a short distance along inner face of tarsus . . . . . Pygochelidon. ... PYGOCHELIDON, Baird. Pygochelidon, BAIRD. (Type Hirundo cyanoleuca.) ... This subgenus differs from its other allies with the nostrils superior, in having the toes more deeply cleft—the basal joint of the median being free at its extremity on the outer side, instead of being adherent to the middle, or even the end of the middle joint. From Petrochelidon it differs in the longer tarsi, which equal the middle toe and half its claw, not the middle toe alone; less completely feathered tarsi at upper end; and in wanting the bristles in the chin and at base of bill above, which are soft and smooth. While the nostrils in Petrochelidon appear in the dried skin to be entirely without membrane, in Pygochelidon they are bordered behind and internally for a short distance, without, however, being overhung. ... Atticora cyanoleuca. ... Golondrina de la timoneles negros, AZARA ... Hirundo melampyga, LICHT. ... Entire crissum from anus black, glossed on surface with steel blue, the bases all dark plumbeous." (Baird 1865).