STRUCTURE OF PIGEON 



733 



External characters. — The form of the body, well suited 

 for rapid flight, ceases to be graceful when stripped of its 

 feathers. The cere above the nostrils, the third eyelid 



-sh 



u 



Fig. 434. — After 

 Nitzsch. 



A, Filoplume. B, Very 

 young feather within 

 its sheath {sh.) ; c, the 

 core of dermis ; b., the 

 barbs. C, The same, 

 external view. 



Fig. 435. — Diagram showing a stage in the 

 development of a feather. 



B., A barb with barbules ; R., the rachis ; EP.\ 

 outermost layer of the epidermis, the stratum 

 corneum, forming^ a sheath for the young feather : 

 £P.2, inner layer of the epidermis, the stratum 

 malpighii, forming the feather ; Q., the quill ; 

 F.F., wall of the feather-follicle; D., the dermis, 

 which enters the base of the feather, forming the 

 pulp (P.). 



in the anterior upper corner of the orbit, the external 

 opening of the ear concealed by the feathers, the preen 

 gland on the dorsal surface at the root of the tail, and the 

 cloacal aperture, are external features easily recognised. 



