_Geographic range._--Micronesia: Mariana Islands--Saipan, Tinian. _Characters._--Adult: Resembles _H. c. teraokai_, but slightly larger; pileum white; white collar broad; black band on nape narrow and faint in some individuals; back and scapulars more oily green and less blue. Immature: Resembles adult, but pileum pale buff streaked with bluish-green; back and scapulars darker; upper wing-coverts edged with white; breast feathers edged with dusky black. _Measurements._--Measurements are listed in table 33. _Specimens examined._--Total number, 20 (12 males, 8 females), as follows: Mariana Islands, USNM--Saipan, 1 (Sept. 27)--Tinian, 4 (Oct. 18, 23, 26); AMNH--Saipan, 11 (July 8, 9, 11, 13, 15, 17, August 5, 21, 26)--Tinian, 4 (Sept. 7, 8, 10). _Nesting._--Hartert (1898:42) records an egg found in a hole of a tree at Saipan on July 31, 1895. He writes that the egg "is only slightly glossy, very thin, pure white, but soiled all over with deep brown spots, evidently from the decaying wood in the nest hole. It measures 33:25 mm." _Molt._--Most of the birds taken in July, August, September, and October are in molt. _Remarks._--Quoy and Gaimard, who visited the Marianas while on the expedition in the "Uranie," obtained this kingfisher at Tinian. Additional material was taken by Marche in 1887 at Saipan and by Owston's Japanese collectors in 1895. In 1932, Coultas (field notes) found the bird to be common on both Tinian and Saipan, especially in open country. At Saipan, Stott (1947:526) found the birds as singles or in pairs on wooded hillsides. At Tinian, Gleise (1945:220) estimated the population in 1945 as 150. The completely white head in _H. c. albicilla_ closely resembles that in _H. s. saurophaga_ Gould of Melanesia. These two species resemble each other in several other respects. _H. saurophaga_ is smaller than _H. chloris_ with black or greenish blue on the anterior part of the ear-coverts and the color of the back, wings, and tail is more greenish. The presence of both _H. saurophaga_ and _H. chloris_ on the same islands in Melanesia is an indication that the two groups are specifically distinct. =Halcyon chloris owstoni= Rothschild White-collared Kingfisher _Halcyon owstoni_ Rothschild, Bull. British Ornith. Club, 15, 1904, p. 6. (Type locality, Asuncion.) _Halcyon albicillus Sharpe_ (part), Cat. Birds British Mus., 17, 1892, p. 249 (Marianne = Pagan, Agrigan). _Halcyon albicilla_ Oustalet (part), Nouv. Arch. Mus. Hist. Nat. Paris, (3), 7, 1895, pp. 169, 170 (Pagan, Agrigan); Hartert, Novit. Zool., 5, 1898, p. 52 (Pagan, Agrigan). _Sauropatis chloris owstoni_ Kuroda, in Momiyama, Birds Micronesia, 1922, p. 59 (Asuncion). _Leucalcyon albicilla owstoni_ Mathews, Syst. Avium Australasianarum, 1, 1927, p. 376 (Asuncion).