Linnæus united under the common title of Pelicans, the Cormorants, the Boobies, and several other birds, which differ from the typical species of the genus by many important characters, the chief point of agreement between them consisting in the form and extent of the membrane which unites the toes. The Linnean group has subsequently been raised to the rank of a family, and its component parts form several distinct genera, that which comprehends the true Pelicans, the genus Onocrotalus of Brisson, being characterized as follows. Their bill is of very great length, straight, broad, flattened above, and terminated by a slight hook; the lower mandible consists of two lateral branches, united at the point, and having interposed between them a membranous pouch capable of very great dilatation; their four toes are all enveloped to the very apex in the common membrane; their legs are short, strong, and maintain the body in a state of equilibrium, their lower part being entirely destitute of feathers. With the exception of the quill-feathers of the wings, which are black, the plumage of the Pelican in the Tower is throughout of an extremely light and delicate flesh-colour, varied only by occasional darker tinges. The head and upper part of the neck are clothed with a short down, except on the temples, which are naked and flesh-coloured; the upper mandible is of a dull yellow in the middle, with a reddish tinge towards the edges, and a blood-red spot on its curved extremity; and the pouch is of a bright straw-colour.