Recently published Ornithological Works. 551 
53. Beebe on the Tail-feathers of the Motmots. 
[Racket-formation in the Tail-feathers of the Motmots. By C. William 
Beebe. Zoologica, vol. i. No. 5. New York, 1910.] 
Mr. Beebe discusses the curious question as to how and 
why the tail-feathers in the Motmots become spatulate. 
That the bird—at least in some cases—assists in the process 
is certain, for it has been caught in the act 33 by such 
trustworthy observers as Waterton, Salvin, and Bartlett. 
Moreover, Mr. Beebe has a living bird that performs the 
operation every year. But the object of this habit is still 
quite unknown. Mr. Beebe is of opinion that a certain 
definite portion of the central rectrices of the Motmot “ has 
a decided degeneration,” so that when the bird preens its 
feathers the barbs and barbules of this portion come easily 
away. This may be true, but why does the “ degeneration 33 
take place? As Mr. Beebe confesses, we cannot tell. But 
his experiments on the tail-feathers of his Motmot are well 
worthy of study. 
54. Beebe on Supernumerary Toes in Birds. 
[Three Cases of a Supernumerary Toe in the Broad-winged Hawk, 
Buteo brcichypterus. By C. William Beebe. Zoologica, vol. i. No. 6.] 
Mr. Beebe describes, and illustrates by photographic 
plates, three instances of an extra toe being present in 
specimens of Buteo brachypterus. It is certainly remarkable 
that this abnormality should occur in three individuals 
obtained in widely different localities. 
55. Clark on the Birds of the North Pacific. 
[The Birds collected and observed during the Cruise of the U.S. 
Fisheries Steamer ‘ Albatross ’ in the North Pacific Ocean and in the 
Bering, Okhotse, Japan, and Eastern Seas from April to December 1906. 
By Austin Hobart Clark. From the ‘ Proceedings ’ of the U.S. National 
Museum, vol. xxxviii. pp. 25-74 (1910).] 
In 1906 Mr. Clark accompanied, as ornithologist, the 
cruise of the U.S. Fisheries Steamer ‘ Albatross 9 in the 
North Pacific. The route out was made by the Aleutian 
