PLUMAGE OF THE NESTLING BARN-OWL. 325 



But in addition to the foregoing structural details I 

 am able to carry the matter a stage further. Mentioning 

 the facts just set forth to my friend Mr. J. L. Bonhote, 

 he kindly sent me a few, but most interesting, notes which 

 he had already made on this same theme. After the 

 appearance of my paper on the Tawny Owl, already 

 referred to, he made a point of settling the down-sequence 

 of the Barn-Owl for himself, and succeeded, by the help 

 of some birds bred by himself in 1909. In a letter to me 

 in the early part of 1911, he writes : " When first hatched, 

 the young Barn-Owl is covered with a very short, close, 

 white down. At about eight or ten days old this down 

 is cast, and the long, white down figured in your book 

 {A History of Birds) makes its appearance. This second 

 down differs from the second plumage of the Tawny Owl, 

 in that it is pure down and not mesoptyle." In this 

 last particular, Mr. Bonhote is mistaken, having under- 

 stood my term " mesojityle " to indicate a feather inter- 

 mediate in structure between a down-feather and a contour- 

 feather. This is not the meaning of the word. The term 

 "tnesoptyle denotes sequence, not structure. Mr. Bonhote 

 continues : " The second down-plumage is, however, 

 soon cast, at about the age of eight weeks, and when the 

 young leave the nest they are practically fully-feathered." 



