2 



VERTEBliATA. 



o 



;—• — D 



wintiT, which coinjx>llecl them to forsake us for more favored climes! Their songs, now heard 

 from till' Irafv jxroves ami shadowy forests, inspire delight or recollections of the pleasing past in 

 every breast. How volatile, how playfully capricious, liow musical and happy, are these roving 

 sylphs of nature, to whom the earth, the air, and the waters, are almost alike habitable. Their 

 A lives are spent in boundless action, 



and nature, with an omniscient benev- 

 olence, has assisted and formed them 

 for this wonderful display of perpetual 

 life and vigor in an element almost 

 their own."* 



A careful examination of the struc- 

 ture of birds will show us that while 

 the vertebrate form is preserved in the 

 skeleton, there is a wonderful adapta- 

 tion of all the parts to the life these 

 animals are to lead. The prodigious 

 strength necessary to the wings is se- 

 cured by powerful muscles attached to 

 the stenimn or breast-bone. As they 

 are to sustain themselves in tlie air, 

 the requisite lightness is obtained by 

 makinof the bones hollow and the cov- 

 ering of feathers. In order to facili- 

 tate respiration, which would otherwise 

 be obstructed in the rapidity of their 

 flight, the air is not confined to the 

 lungs, as in other animals, but passes 

 through into various membraneous 

 cells exterior to the heart, and in some 

 cases is extended even down the wings. 

 Birds, as well as quadrupeds, may 

 be generally divided into two great 

 classes, accordinsj to their food, some 

 being Carnivorous, as eagles, owls, and 

 vultures, and others being Granivorous, 

 as quails, grouse, pheasants, and do- 

 mestic fowls; many, also, hold a mid- 

 dle place, and may be called Omniv- 

 orous. Taken together, the food of 

 birds is extremely varied, including 

 fish and flesh, amphibia, reptiles, in- 

 sects, fruits, grains, seeds, roots, and 

 herbs. In the structure of the digest- 

 ive organs, they exhibit a great uni- 

 formity. The oesophagus, which is often very muscular, is usually dilated into a large sac, called 

 the Crojy, at its entrance into the breast ; this is abundantly supplied with glands, and acts as a 

 sort of first stomach, in which the food receives a certain amount of preparation before being sub- 

 mitted to the action of the proper digestive organs. A little below the crop the narrow a?sopha- 

 gus is again slightly dilated, forming what is called the venirkulus succentitriafus, the walls of 

 which are thick, and contain a great number of glands, which secrete the gastric juice. Below 



SKELETON OP SPAEROW-nA'WK. 



A, Cranium or Sknll. B, Cervical vertebrae. 



C, The dotted lines indicate the extent of the anchylosed vertebrae of the baefc. 



D, The caudal vertebrae ; the letter is placed on the j)lowshare or rump-bone. 



E, Ribs. F, Sternum, or breast-bone. G, Furcula, or merry-thought. 

 H H Clavicular, or coracoid-bone, ) ^^^^ the sidesman. 



H*, Scapula, or shoulder-blade, ) = 



I, Humerus, or bone of the arm. 



K, IHna, i Bones of the fore-arm : on the ulna is the place of insertion of the 



L, Radius, f secondary quills. 



M, Metacarpal bones, part of the hand which carries the primary quills. 



N, Phalanges of the fingers. 



O, Ilium, I 



P, Pubis, V Bones of tie pelvis. 



Q, Ischium. ) 



K. Femur, or thigh-bone. o o. Patella, or knee-pan. 



S, Tibia and fibula, or leg-bones consolidated. T T, Os calcis, or heel-bone. 



V V, Metatarsal, or shank-bones. W W, Toes. 



♦ See " Manual of the Ornithology of the United States and Canada," by Thomas Nuttall, Cambridge, Massa- 

 chusetts. 1834. 



