FAMILY III.—THE AUKS (ALCIDÆ).
| Sub-Family | 1.—The Auks (Alcinæ). |
| " " | 2.—The Crested Divers (Phaleridinæ). |
| " " | 3.—The Penguins (Spheniscinæ). |
| " " | 4.—The Loons (Urinæ). |
FAMILY IV.—THE PETRELS (PROCELLARIDÆ).
| Sub-Family | 1.—The Petrels Proper (Procellarinæ). |
| " " | 2.—The Albatrosses (Diomedeinæ). |
FAMILY V.—THE GULLS (LARIDÆ).
| Sub-Family | 1.—The Gulls Proper (Larinæ). |
| " " | 2.—The Scissor-bills (Rhynchopinæ). |
| " " | 3.—The Terns (Sterninæ). |
FAMILY VI.—THE PELICANS (PELICANIDÆ).
| Sub-Family | 1.—The Tropic Birds (Phaetoninæ). |
| " " | 2.—The Darters (Plotinæ). |
| " " | 3.—The Pelicans Proper (Pelicaninæ). |
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