NATATORES. 477 



members of the family, they inhabit northern and polar re- 

 gions. * 



In the Divers {Colymbidm), comprising the true Divers and 

 the Grebes, the power of flight is pretty well developed, but 

 the bird still is much more active in the water, swimming or 

 diving, than on land. The Grebes are not uncommon in Bri- 

 tain, and are largely killed for making muffs, collars, and other 

 articles of winter dress. They have the membrane between 

 the toes deeply incised. They haunt the sea as well as lakes 

 and rivers, and swim and dive admirably. In the Divers pro- 

 per the front toes are completely united by a membrane. The 

 Northern Diver or Loon ( Colymbus gladalis) is a familiar ex- 

 ample, and is found on the coasts of high northern latitudes. 



Fam. 2. Longipennafce. — This {axmly oi Natatores is charac- 

 terised by the well-developed wings, the pointed, sometimes 

 knife-like, sometimes hooked bill, and by never having the 

 hallux united with the anterior toes by a membrane. The 

 following are the more important groups coming under this 

 head : — 



a. Larida, or Gulls and Terns, having powerful wings, a free 

 hinder toe, and the three.anterior toes united by a membrane. 

 The gulls form an exceedingly large and widely distributed 

 group of birds ; and the Terns or Sea-swallows are equally 

 beautiful, if not quite so common. The Terns are distinguished 

 by their long and pointed wings, forked tail, and comparatively 

 short legs. They fly with great rapidity over the surface of the 

 sea, from which they pick up their food. 



b. Procellarida, or Petrels, closely resembling the true Gulls, 

 but having a rudimentary hinder toe, and having the upper 

 mandible strongly hooked. The smaller species of Petrel are 

 well known to all sailors under the name of Storm-birds and 

 Mother Carey's Chickens. They are nocturnal or crepuscular 

 in their habits,, breed in holes in the rocks, lay but one egg, 

 and are almost all of small size and more or less sombre 

 plumage. The largest member of the group is the gigantic 

 Albatross {Diomedea exulans), not uncommonly found far from 

 land in both the northern and southern oceans. The Albatross 

 sometimes measures as much as fifteen feet from the tip of 

 one wing to that of the other, and the flight is powerful in 

 proportion. 



Fam. 3. Tatipalmatce, characterised by having the hinder 

 toe or hallux more or less directed inwards, and united to the 

 innermost of the anterior toes by a membrane (fig. 185, A). In 

 this family are the Pelicans, Conuorants, Gannets, Frigate- 

 birds, Darters, and others. They all fly well, and have short 



