749A. SITKA KINGLET. _Regulas calendula grinnelli._ Range.--Pacific coast, breeding in Alaska. Said to be brighter than the preceding variety. 749b. DUSKY KINGLET. _Regulus calendula obscurus._ Range.--Guadalupe Island, Lower California. This species nests during March in the large cypress and pine groves at high elevations above the ground. The nests are similar in construction to those of the common Ruby-crown, and the eggs are scarcely different from some specimens of that species; white, dotted and wreathed with reddish brown. Size .56 × .43. 751. BLUE-GRAY GNATCATCHER. _Polioptila cærulea cærulea._ Range.--United States, east of the Rockies, breeding from the Gulf to the Middle and Central States; casually north to Massachusetts and Minnesota. These graceful birds are bluish gray above with a black forehead and central tail feathers, and white underparts. They are common in wooded districts in the south, where they saddle their beautiful nests upon horizontal branches or in crotches usually at quite an elevation from the ground; they resemble large Ruby-throated Hummers' nests but the walls are much higher and thicker; they are made of plant fibres and down, lined with cottony substances and hair, and covered on the outside with lichens to match the limb upon which it is placed. Their eggs are bluish white, specked with reddish chestnut. Size .58 × .45. Data.--Chattanooga, Tenn., April 30, 1900. Nest of moss, covered with lichens and lined with hair and feathers; 20 feet from the ground in a small tree. 751a. WESTERN GNATCATCHER. _Polioptila cærulea obscura._ Range.--Western United States and Lower California. The habits and eggs of this sub-species are the same as those of the eastern bird, and the nests do not differ except, perhaps, in less ornamentation of the exterior. 752. PLUMBEOUS GNATCATCHER. _Polioptila plumbea._ Range.--Mexican boundary from western Texas to southern California. This species has a bright shining black crown and more black on the tail than the eastern Gnatcatcher. They saddle their nests upon the branches of trees or in upright forks, usually at an elevation of ten feet or more from the ground; the nests are made of plant fibres and fine bark strips, compactly felted together, and with little, if any, ornamental lichens on the exterior. Their eggs are pale greenish blue, spotted with reddish brown, and vary from three to five in number. Size .54 × .44. [Illustration 443: Ruby-crowned Kinglet.] [Illustration: Bluish white.] [Illustration: Greenish blue.] [Illustration: right hand margin.] Page 442 753. BLACK-TAILED GNATCATCHER. _Polioptila californica._ Range.--Pacific coast of southern California and northern Lower California.