742 



THE PTERYLOGRAPHY OF THE RUFFED GROUSE 



line. The thick, lonp. aftershafted feathers in the interscapular and ])c>sterior regions provide 

 excellent protection. 



Oil Gland. This tract is small, consisting of eight small feathers arranged in a circle sur- 

 rounding the apex of the oil gland. 



Caudal. The caudal tract is made u|) of the large rectrices. their coverts, and the feathers 

 surrounding the anus. The rectrices make up the tail proper, although the middle pair has 

 been crowded out of line dorsally. Usually eighteen are found, but deviations from this num- 

 ber are not particularly rare. Birds having twenty are usually large males while those with 

 sixteen are usually females. The number is not associated with age since twenty have been 

 found in young birds. Neither is it a subspecific character. 



Protecting the bases of the large tail feathers on the upper side are the upper-tail coverts. 

 These lie in a single row and usually comprise eight pairs, occasionally nine. They separate 

 two rows of small, down-like feathers. 



At the base of the tail, underneath, are the under-tail coverts consisting of about five 

 rows. Those of the first row (nearest body) are very small. The second, third, fourth and 

 fifth rows contain much larger feathers, but gradually decrease in size in that order. A space 

 occupies the middle line. 



The anus is surrounded bv small tuft-like feathers. 



Venlral. The entire ventral surface of the body, from the lower jaw to the anal region, is 

 included in this tract. In the majoritv of birds it continues posteriorlv over the breast and 



CORONAL REGION 



OCCIPITAL REGION 

 - POST- AURICULAR REGION 



CERVICAL REGION 



HUMERAL TRACT 



SPINAL SPACE 



FEMORAL TRACT 



CRURAL TRACT 



"PEOAL" TRACT 



INTER-RAMAL REGION 

 SUB-MALAR REGION 



CERVICAL REGION 



INFERIOR SPACE 



DORSAL VIEW 



FICURK !!2. FKATIIKK TRACKS AND SPACES OF TIIK Rl FFED CROISE 



