Pterylosis of Harris's Woodpecker. 



A. Dorsal aspect of the same specimen shown in Fig. CS; &, capital apterium; c, the median (at 

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

 it; g, spinal tract;./', inner humeral tract; e, humeral tract; //, lower dilation of spinal tract (the saddle) ; 

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

 pecker);^, caudal tract; 7, alar L tract. B. Anterior or ventral aspect of the same specimen, with 

 its head turned to the left; <t, capital tract; it, the ventral tract, and m, its external branch. All the 

 figures drawn by the Author from the specimen. 



