346 Mr. W. P. Pycraft on the 



tinuous tract, more or less completely investing the neck. 

 There is a distinct tendency to form a j)t. colli dorsalis and 

 pt. colli ventralis (see footnote), in that the feathers in the 

 mid-dorsal line stand closer together than on the sides of the 

 neck, in which region they are somewhat sparsely distributed, 

 thus suggesting an incipient differentiation into the usual 

 dorsal and ventral tracts (see footnote). 



Pt. ventralis (PI. IX. figs. 2, 3, P/.v.).— This tract com- 

 pletely invests the whole of the upper part of the breast, 

 rather below the middle of this region ; that is to say, a short 

 distance above the sternal callosity (p. 352) it divides into 

 two widely separate and very narrow branches, which, gra- 

 dually expanding, terminate a short distance in front of the 

 cloacal aperture. This tract is noticeable throughout for the 

 sparseness with which the feathers are distributed. 



Pt. ani (PI. IX. figs. 2, 3, Pt.a.).—A circlet of small fea- 

 thers surrounding the cloacal aperture. 



Pt. humeralis (PL IX. fig. 1, Pt.h.). — A clearly defined, 

 though small and slightly developed, tract of some two or 

 three feathers in width. The constituent feathers are but 

 slightly stouter than those of the pt. spinalis running down 

 beside it, but they are very long, the most posterior and 

 longest reaching nearly down to the tail. Passing forwards 

 and downwards this tract is lost in the upper portion of the 

 pt. ventralis. 



Pt.femoralis (PI. IX. figs. 1-3, Pt.f.). The feathers of this 

 tract are very long and sparsely distributed ; it is connected 

 both with the pt. spinalis and pt. cruralis. 



Pt. cruralis (PI. IX. figs. 1-3, Pt.cr.). — This tract is com- 



ueck-tract is continuous ; ■when, as in the typical arrangement, the tract 

 is divided into a dorsal and a ventral band, I would distinguish the former 

 as the pt. colli dorsalis and the latter as the pt. colli ventralis. 



Pt. colli is a new name recently adopted by Dr. Gadow in Prof. Newton's 

 ' Dictionary of Birds,' and should be gratefully welcomed. Up to the 

 present the neck-tracts have been described simply as the dorsal and 

 ventral moieties of the spinal and ventral tracts ; although this system 

 was perfectly correct, yet, as those who speak from practical experience 

 know, it was not always convenient. 



