Bill unserrated, and ending in a nail. Nostrils united externally in one tube above the culmen. Margin of sternum even. Second primary longest. The majority of Petrels on being captured vomit a small quantity of clear oil with a disagreeable smell. The plumage of the Petrels is somewhat close set, and a peculiar musky odour is perceptible in all of the species. The same smell attaches to the eggs, and seems never to evaporate entirely.