Passing over several smaller genera, we come to another large genus of Petrels (AEstrelata), the members of which are rather closely allied to the Shearwaters, but from which they differ in having a shorter and stouter bill, a very thin partition between the nostrils, relatively shorter nasal tubes, and a very large “nail,” which occupies at least one third the total length of the lower mandible. The plumage and size in the thirty or more species is very variable. They are natives mainly of the temperate and tropical portions of the oceans of the Southern Hemisphere, coming northward in the Atlantic casually to the British Islands and the Middle Atlantic States, and in the Pacific to Alaska and Japan. One of the North American species is the Black-capped Petrel (AE. hasitata), a bird about fifteen inches in length, sooty brown above, with the crown black and the back of the neck, upper tail-coverts, and whole under surface pure white. It ranges from the West Indies to Florida and Long Island, but almost nothing is known of its history or habits. Another species, known as the Dark-rumped Petrel (AE. Phaeopygia), occurs in the middle Pacific, from the Hawaiian Islands to the Galapagos. Perhaps the handsomest as well as the rarest species is Fisher’s Petrel (AE. fisheri) of the North Pacific in the vicinity of Kodiak, Alaska. It is uniform bluish gray above, the top of the head white, spotted with grayish, while the cheeks, chin, throat, middle of the chest, and under tail-coverts are pure white, and the lower breast, abdomen, and flanks smoky lead-colored superficially, but with the feathers all pure white immediately beneath the surface. It is only known from the type specimen.