2 1 A. Correapoudence. [April 



Splivrapicus v. niichalis^ and it is a well-known fact that in this Wood- 

 pecker the limbs of the hj'oid arches are nearly or quite as short as we find 

 them in ordinary birds. 



Another apterium, also alluded to by Nitzsch, and occurring on the 

 sides of the head, is the temporal space ; this small, subcircular, naked area, 

 when present, is found just behind the eye and above the aperture of the 

 'iar. It was not observed by me in the specimen of Harris's Woodpecker 

 shown in Fig. i, but recent and more extended observations lead me to 

 believe that it is a quite constant pterylographic character in this species. 

 On the other hand, I have yet to find it present in Spkyrapicus, although 

 I do not positively deny that there may be exceptions to this rule like- 

 wise. It is invariably present in Colafies, a picine form which also has 

 the longitudinal capital apterium well marked. The remainder of the 

 head in Pici, so far as the writer has examined them, is always found to be 

 densely feathered (Fig 4). 



Among Woodpeckers the spinal tract offers us many and important va- 

 riations (see Fig. 2,^, h,j, and Fig. 5). Nitzsch discovered so many 

 differences in this particular in the species he examined that it will be im- 

 possible to enumerate them here. Figure 2 shows very well the distribu- 

 tion of the spinal feather tract in D. v. Iiarri>ii\ and Fig. 5, the interesting 

 departure therefrom in Sphyrapicus, in which latter species the arrange- 

 ment is much the same as we find it to be in many typical passerine birds. 

 In Picas -oiridis an interruption takes place between the narrow median 

 neck strip of the spinal tract and the 'saddle area' (//), and in Colaptes 

 this feature is likewise fairly well marked. Colaptes again has the pos- 

 terior moiety of the spinal tract, just as we find it to exist in Dryobnfes, as 

 shown in Figure 2, at J. As far as I know all Woodpeckers have a strongly 

 tufted oil gland (Fig. i, /). 



Faintly marked as a rule in all Vici, the fetnoral iracf in Colafies agvees 

 in being but feebly traceable by the presence, on either side, of a few 

 downy feathers, and at the most not more than some three or four contour 

 ones. Like Dryobates, however, Colaptes possesses on either leg, a well- 

 defined 'crural tract,' occupying a position similar to the one we find it 

 in in the majority of Woodpeckers (Fig. 2, z"). Nitzsch, as I have else- 

 where stated, found the 'inner humeral tract' (Fig. 2./) absent only in 

 the Sumatran species, which he described as Pictis luridus; this charac- 

 teristic and sharply defined though small feather area is present in all spe- 

 cies of Colaptes, as it is in every American Woodpecker that the writer 

 has ever submitted to a pterylographic examination. On the outer side 

 of this smaller humeral tract we also find, in every species of Woodpecker, 

 the larger 'humeral tract' proper, which, as is usual, passes obliquely 

 across the region of either shoulder, as shown in Figure 2 at e, and in 

 Figure 5, where it is likewise well marked. If we carefully examine, we 

 shall find very sparsely appearing feathers, for the most part downy ones, 

 showing themselves here and there on the apteria among the dorsal areas. 

 No special description is needed here for the 'alar tracts' in these birds, 

 and we can next turn to the ventral aspects of the specimens under con- 

 sideration. Here we find the feather areas very well defined, more espe- 



