PLATK VIII. 



FEATHERED TRACTS AND UNFEATHERED SPACES IN BIRDS. 



Although the feathers of a bird lay over each other hke shiugles ou a roof it does 

 notfollow that they grow everi/wherc upou the skin. Feathers grow iu tracts with bare 

 spaces between. A uniform and continuous feathering, however, occurs in some 

 birds as, in the ostriches, penguins, and toucans. Some birds, to be sure, are naked 

 about the head or feet. 



Figures A and B in our plate are taken fi-om a siDecimen of the Flicker Colapes 

 auratus, A representing the under portion and B the upper part of the bird's feath- 

 ering. Fig. 1 is the capital tract which clothes the head and generally joins the 

 dorsal and ventral tracts. Fig. 2, alar tract, all the feathers which grow on the wing, 

 except the humeral tract. Fig. 3, humeral tracts, being the place where the beginner 

 often fails to make the feathers of the shoulders lay as they do in life, caused chiefly 

 by making the artificial body too full at this point. Fig. 4, spinal or dorsal tract, 

 running along the middle of the bird Irom above the nape of neck to the tail, subject 

 to great variation. Fig. 5, femoral tracts, band upon outside of each thigh, subject 

 to great variation. Fig. 6, leg tract covers the legs as far as these are feathered, gen- 

 erally to the heel, always below the knee and sometimes to the toes as in many owls. 

 Fig. 7, ventral tract, the plumage along the belly and under parts commencing at or 

 near, and frequently running into the dorsal tract, but subject to great variation in 

 forms. Fig. 8, the tail or caudal tract, includes the feathers ot the tail, their coverts 

 and those about the elcrodochon, and usually join the termination of the dorsal, ven- 

 tral and femoral tracts. Fig. 9, represents the salivary glands so wonderfully devel- 

 oped in woodpeckers. 



