44 STRUCTURAL AND SYSTEMATIC ZOOLOGY 



compare with the fish and the frog ; the head, its shape 

 and various parts composing it, the jaws, eyes, nostrils ; 

 note the absence of teeth ; the tongue. 



Remove the lower half of the shell and study the 

 internal organs composing the digestive, circulatory, 

 reproductive, and excretory systems; compare the 

 structure of the heart with that of the fish and the 

 frog (Fig. 273). 



On a skeleton note the various parts which are 

 attached to the shell ; the skull and neck ; the hyoid 

 apparatus, the structure of the limbs and tail ; compare 

 the hyoid apparatus and the ribs with those of the frog 

 (Fig. 312). 



If eggs can be obtained, note the shape, structure of 

 the shell, and the stages of development of the young. 



Bird 



Sparrows or pigeons may be used. 



Field Study. Note its general mode of life, whether 

 solitary or gregarious ; relations to other birds and to 

 man ; its manner of flight and of walking ; feeding 

 habits ; size, shape, and coloration of the body ; varia- 

 tions in coloration at different seasons of the year; 

 position and structure of the nest, number, shape, size, 

 and color of eggs, number of broods each year, season 

 when broods are produced, and number of young in 

 each brood ; enemies ; song ; if a living specimen can 

 be obtained, test the body temperature with a ther- 

 mometer. 



Structure. With a recently killed specimen, study 

 the shape of the body, the direction of its axis ; the 

 position and mobility of the head, wings, legs, and tail ; 

 the distribution of the various feathers, their structure 

 (Figs. 139, 302). Remove the latter and note the feather 

 tracts and the skin. Study the shape and structure of 



