Lesson VI.] 



NATURAL HISTORY. 



principles of classification. The characteristics of each order, genus, and species, will 

 be given in the Catechism on ZOOLOGY ; and the remaining portions of Natural History, 

 in those on BOTANY and (M:>I.(H.Y. Our present object is to consider the second class 

 of vertebrate animals Aves, or birds. 



In classifying the birds, naturalists attend to the form of the extremities and the bill. 

 In some birds, we see the bill and claws sharp, hooked, and powerful ; as in the eagle 

 and Egyptian neophron, adapted for tearing the flesh and holding the prey ; in others, 



K t . T. fit- S.f Fig. 9.1 



the beak is short and thick, suited for crushing hard seeds, as in the parrots and loriets ; 

 while some have long slender bills, or soft short ones, fitted for feeding upon insects. 

 The bill varies in length, breadth, and direction, as well as shape. The feet also differ 

 materially: thus we have perching, climbing, wading, and swimming foot. In addition 

 to these means of classifying the birds, the naturalist has to call to his aid the appear- 

 ance of the crests, eyes, ears, mouth, feathers, wings, and tail. The whole structure of 

 this class of animals is peculiarly adapted for motion in the element the mass of them 



QUESTIONS. 



74. T. Is there anything peculiar in the 

 structure of birds ? 



P. Yes; the general adaptation of the 

 . .trk to the purposes of life, 

 and the covering of the body. 



/' Why is the body covered with 

 feath. 



P. Because they are bad conductors of 



rapidly, tl 

 bodies is not decreased too suddenly. 



76. T. Do they possess a complete 



P. Yes, and are called warm-blooded 

 animals. 



/' How is the bo ; light? 



/*. By the interior of th, 

 hollow, and containing air, which lenem 

 their specific gravity. 



78. 7*. Can y- s h a water- 



bird from another, and ' 



P. Yes: by the form of its feet, and 

 other peculiarities. 



[Tho pupil should name them.] 

 79. T. Is then at difference 



in the form of a ,1's feet from 



those of a swimming-bird .' 



I'. Yes. Tin- former h.ivc long slender 

 legs, bare ot md long straight 



toes ; while the lat;> 



! by a web, which forms 

 abroad surface \\!.. hat the 







' legs, arm 

 powerful, sharp, and hooked talci 



l 

 front ; and th- perching birds have three 



hind, anil ' 



:ies arc united by a very short mem- 

 the toes are long, with long claws 



I lave natura' 



Ity in the subdivision of the 

 class Avc-s ? 



I. S. U.d of llarpjria dt.tructoc. 

 I /'; 9. II vail of Pesopor .. fortMSW. 



