NATATORES. CATARACTES. 518 
sessed by the former), are developed in their structure, par- 
ticularly in the bill, feet, and tail, and as a marked differ- 
ence also exists in their habits, it has been considered neces- 
sary to establish a distinct genus for their reception. This 
has been done by Inticer, in his Prodromus, under the ge- 
neric name of Lestris, in which he has been followed by Trm- 
MINCK, and several other writers; but as our countrymen, 
Witiovcusy and Ray, had previously separated them from 
the genus Larus, under the appellation of Cataractes, I have 
followed the rule so generally adopted by naturalists, that of 
acceding to priority of imposition. In the cereous or soft 
horny covering of the basal part of the bill, the acuminate 
feathers of the neck, and their strong hooked talons, the 
Skuas exhibit a distant affinity to birds of the raptorial or- 
der, and their bold disposition and daring habits are also in 
apparent accordance with this connexion. They are the de- 
termined enemies of the Gulls, whom they unceasingly per- 
secute on the wing, in order to make them disgorge their 
half digested or recently swallowed food, and which is then 
adroitly caught by the former before it can reach the water. 
They also feed upon the flesh of the whale and other marine 
animal substances. An approach to the Petrels is seen in their 
general contour, and in the structure of their feet, the hind 
toe in some species consisting of little more than a nail. 
Their wings are long and pointed, and their flight, which is 
strong, and at times astonishingly rapid, is performed by 
successive jerks (in each of which a considerable curve is de- 
scribed), bearing but little resemblance to that of the true 
Gulls. They are natives of the Arctic Regions, and are found, 
particularly during the season of reproduction, in very high 
latitudes. The plumage of both sexes is alike, but some 
species undergo great changes in their progress to maturity. 
VOL. II. Kk 
