This species, while not common, nests in all manner of localities on the Farallones, concealing their eggs under any rock or in any crevice that may attract their fancy. Their single white egg is only faintly if at all wreathed with fine dust-like specks of reddish brown. Size 1.15 × .86. Data.--Farallone Is., California, June 12, 1895. Egg laid on sand in crevice at the base of a stone wall; well concealed. Collector, Chester Barlow. 108.1. SOCORRO PETREL. _Oceanodroma socorroensis._ Breeds on Socorro, San Benito and Coronado Islands, placing its eggs at the end of burrow. Data.--San Benito Is., Lower California, July 12, 1897. Single egg at the end of a burrow 3 feet in length. Egg pure white very finely wreathed with pale reddish brown. Size 1.15 × .87. Collector, A. W. Anthony. [Illustration 072: Black Petrel. Ashy Petrel.] [Illustration: deco.] [Illustration: left hand margin.] Page 71 109. WILSON'S PETREL. _Oceanites oceanicus._ Breeds in the southern hemisphere in February and March and spends the summer off the Atlantic coast as far north as Newfoundland. This species can be distinguished from Leach Petrel by its square tail and from the Stormy Petrel by its large size and yellow webs to its feet. These birds are the greatest wanderers of the genus, being found at different seasons in nearly all quarters of the globe. Their single egg is white. Size 1.25 × .90. 110. WHITE-BELLIED PETREL. _Fregetta grallaria._ A small species (length about 7.5 inches) inhabiting southern seas. Recorded once at Florida. General plumage blackish. Upper tail coverts, bases of tail feathers, under wing coverts, and abdomen, white. 111. WHITE-FACED PETREL. _Pelagodroma marina._ Range.--Southern seas, accidentally north to the coast of Massachusetts. This beautiful species is of about the same size as the Leach's Petrel. It has bluish gray upper parts; the whole under parts, as well as the forehead and sides of head, are white. These birds have the same characteristics as do others of the species, pattering over the water with their feet as they skim over the crests and troughs of the waves. They are not uncommon in the waters about New Zealand where they breed. Their single eggs are about the same as Leach's Petrel, are brilliant white and are, very strongly, for a Petrel egg, wreathed about the large end with dots of reddish brown. Size 1.32 × .90. Data.--Chatham Is., New Zealand, January 7, 1901. Egg laid at end of a burrow. Collector, J. Lobb. This egg is in Mr. Thayer's collection. [Illustration 073: Wilson's Petrel. White-billed Petrel. White-faced Petrel.] [Illustration: White.] [Illustration: deco.] [Illustration: right hand margin.] Page 72 TOTIPALMATE SWIMMERS. Order IV. STEGANOPODES TROPIC BIRDS. Family PHAETHONTIDAE Tropic Birds are Tern-like birds, having all the toes connected by a web, and having the two central tail feathers very much lengthened. 112. YELLOW-BILLED TROPIC BIRD. _Phæthon americanus._