282 



VERTEBRATES : BIRDS. 



compressed and acute, tail short and rounded. Birds oi 

 this genus excel all others in diving and in making pro- 

 gress beneath the surface of the water. They are solitary, 

 keen-sighted, and wary. 



The Great Northern Diver, or Loon, C. torquatus, 

 Briinn, of North America, is thirty-one inches long, and 

 the wing fourteen inches. The Black-throated Diver, 

 C. arcticus, Linn., of the northern regions, is about twenty- 

 eight inches .long, and the wing twelve and a half inches. 

 The Red-throated Diver, C. septentrionalis, Linn., of the 

 Fig. i 4 8. northern regions, is twenty-seven 



inches long, and the wing eleven 

 and a half inches. 



The Genus Podiceps Grebes 

 has the bill long, slender, and point- 

 ed ; the head in the spring orna- 

 mented with tufts. These birds fre- 

 quent lakes, rivers, and the sea-coast. 

 When alarmed, they remain beneath 

 the surface of the water, exposing 

 only the bill. Nine species belong 

 to North America, varying from thir- 

 teen to twenty-nine inches in length. 

 The Crested Grebe, P. cristatus, 

 Lath., of North America, is twenty- 

 three and a half inches long, the wing seven and three 

 quarters inches ; umber brown above, silvery white below. 

 The Genus Podylimbus has the bill short, and head 

 without ruffs. It contains the Pied-bill Grebe, P. podi- 

 ceps, Lawr., of North America, which is fourteen inches 

 long, and the wing over five inches. 



ALCIM:, OR AUK FAMILY. This Family comprises 

 swimming birds which have the bill compressed and 

 pointed, hind toe usually wanting, wings very short, and 

 the legs placed far back. They are all marine, and con' 



Crested Grebe, 

 P. cristattts, Lath. 



