SUBFAMILY REGULINÆ. CHAR. Wings longer than the emarginated tail. Tarsi booted, or without scutellar divisions. This subfamily embraces but a single well-defined North American genus. GENUS REGULUS, CUV. _Regulus_, CUV. “Leçons d’Anat. Comp. 1799, 1800.” (Type _Motacilla regulus_, LINN.) _Reguloides_, BLYTH. 1847. (Type “_R. proregulus_, PALL.” GRAY.) _Phyllobasileus_, CAB. Mus. Hein. I, 1850, 33. (Type _Motacilla calendula_, LINN.)—_Corthylio_, CAB. Jour. Orn. I, 1853, 83. (Same type.) [Line drawing: _Regulus satrapa._ 28784. ♂] GEN. CHAR. Bill slender, much shorter than the head, depressed at base, but becoming rapidly compressed; moderately notched at tip. Culmen straight to near the tip, then gently curved. Commissure straight; gonys convex. Rictus well provided with bristles; nostril covered by a single bristly feather directed forwards (not distinct in _calendula_). Tarsi elongated, exceeding considerably the middle toe, and without scutellæ. Lateral toes about equal; hind toe with the claw, longer than the middle one by about half the claw. Claws all much curved. First primary about one third as long as the longest; second equal to fifth or sixth. Tail shorter than the wings, moderately forked, the feathers acuminate. Colors olive-green above, whitish beneath. Size very small. We are unable to appreciate any such difference between the common North American _Reguli_ as to warrant Cabanis in establishing a separate genus for the _calendula_. The bristly feather over the nostril is perhaps less compact and close, but it exists in a rudimentary condition. The following synopsis will serve as diagnoses of the species:— Head with entire cap in adult plain olivaceous, with a concealed patch of crimson. _Hab._ Whole of North America; south to Guatemala; Greenland … _calendula._ Head with forehead and line over the eye white, bordered inside by black, and within this again is yellow, embracing an orange patch in the centre of the crown. _Hab._ Whole of North America … _satrapa._ Head with forehead and line through the eye black, bordered inside by whitish, and within this again by black, embracing an orange-red patch in the centre of the crown. _Hab._ Banks of Schuylkill River, Pennsylvania … _cuvieri._ Regulus satrapa, LICHT. GOLDEN-CROWNED KINGLET.