228 ME. W. P. PrCEAFT ON THE 



feather became either a true contour-feather, in which the Fila became more and more 

 perfectly specialized to form " Hooklets," at the same time as the shaft, rami, and radii 

 increased in strength, or it became a true down-feather. In the latter case the change 

 might be brought about in two ways : — (1) the radii became relatively weaker and more 

 numerous, and the fila of the radii became metamorphosed in various ways, or (2) the 

 shaft became very considerably shorter and weaker. Umbelliform (" doldenformige ") 

 dowu-feathers represent reduced long-shafted feathers. The same, he thinks, may be said 

 of umbelliform neossoptiles. As to whicli is the older of these two primitive types of 

 long-shafted feathers we know at this time nothing for certain. 



In the course of his paper on the distrihution of feathers Meijere briefly discusses the 

 arrangement of the feathers covering the tarso-metatarsus of a young Barn Owl. These 

 he describes as seated in groups of three, a median and two lateral, under the anterior 

 margin of the scales of the podotheca. Such an arrangement recalls, he reminds us, 

 that which obtained on the scaly tail of Mns decumanus. The median feather was much 

 the largest ; the two lateral repi*esented degenerate contour-featiiers sunk to the level of 

 filoplumes. On the tibio-tarsus the feathers are also described as arising in groups of 

 three, but the median feather is here mucli more developed, possessing a distinct though 

 seraiplumous vane. In an adult Barn Owl the lateral feathers of the scales of the podo- 

 theca were wanting or occurred sparingly. Down-feathers and degenerate filoplumes are 

 described as occurring on the dorsal apterium. On the breast filoplumes are stated to 

 occur sjjaringly. 



I find myself vmable to confirm one or two small points in this paper, inasmuch as 

 after careful search I failed to find more than a single filoplumu to each feather on the 

 tibio-tarsus, nor could I succeed in finding any filoplumes associated with the down- 

 feathers of the Owls examined by me. 



As touching matters of identification, it seems to me that Meijere has failed to distin- 

 guish between true down-feathers and semiplumes. The latter occupy the position of 

 and represent contour- feathers which are in process of degeneration and final disappear- 

 ance — the modus ojjerandi of the formation of pterylJB. Down-feathers occupy the spaces 

 between contour-feathers. This makes it rather difficult to accept the hypothesis that 

 thev are degenerate contour-feathers. 



III. Pteroltsis of the Adult. 



Asio ACCIPITRINUS, Pall. (PI. 25. figs. 1-3.) 

 PterylcB : — 



Fteryla capitis. — For the purposes of convenience in description this tract will be 

 described throughout under the following subdivisions : — 



Fronto-parietal are a. — This extends from the base of the beak to the crown of 

 the head. It is clothed by a narrow median band of feathers, expanding later to cover 

 the occipital area. On either side of this median band, in the region corresponding 

 with the level of the superior limb of the crescentic membranous folds surrounding the 



