FIG. 69. PTERYLOSIS OF HARRIS'S WOODPECKER. 



A. Dorsal aspect of the same specimen shown in Fig. 68; 6, capital apterium; c, the medianf(at 

 the point indicated) elevation of the skin caused by the epibranchials of the hyoidean apparatus beneath 

 it; </, spinal tract;/, inner humeral tract; , humeral tract; A, lower dilation of spinal tract (the saddle) ; 

 j, lower part of spinal tract (rump tract); ?', crural tract; o. femoral tract (very faintly seen in a wood- 

 pecker i;p, caudal tract; <?, alar .tract. B. Anterior or ventral aspect of the same specimen, with 

 its head turned to the left; a, capital tract; n, the ventral tract, and m, its external branch. All the 

 figures drawn by the Author from the specimen. 



