Vo, 'i9i9 XVI ] Nichols, Warbler Problems. 225 



the rough tarsus to the bird's habit of roosting in trees, but under 

 Crypturus variegatus (Wagler) (Ibid., p. 748) says that he does not 

 know whether that species also passes the night in trees. More 

 recently F. P. and A. P. Penard, under the names Tinamus sub- 

 cristatus (I. c. 1908, i, p. 318) and Crypturus variegatus (Ibid., p. 322) 

 definitely state the bearing of the construction of the tarsi in these 

 two genera upon the dissimilarity in roosting habits. 



Mr. Beebe's discoveries in regard to the homes of Toucans, also, 

 are extremely interesting, although the state of affairs regarding 

 our knowledge of the life history of Toucans was really not so 

 scanty as conveyed by the few words of Levaillant which the author 

 quotes. It may be of interest to call attention here to a Toucan 

 egg said to be of Ramphastos ariel Vigors, collected by Krone at 

 Iguape, and recorded by Ihering (Rev. Mus. Paulista, 1900, iv, 

 p. 262). It is described as oval, measuring 37 X 28 mm., white, 

 with deep pits on the surface. Schomburgk, Burmeister, and 

 others from time to time, have mentioned Toucan eggs, but beyond 

 saying that the eggs were white, two in number, laid in holes in 

 trees, they did not give much information. 



In concluding I wish to emphasize that I appreciate fully Mr. 

 Beebe's good work at the research station in British Guiana, and 

 my remarks should not be construed as having been made with the 

 purpose of depreciating the excellent publication, of which I have 

 discussed, after all, only some very unimportant details. 



PROBLEMS SUGGESTED BY NESTS OF WARBLERS OF 

 THE GENUS DENDROICA. 



BY JOHN TREADWELL NICHOLS. 



The genus Dendroica with center of abundance in eastern North 

 America, containing numerous closely related birds, inhabiting 

 in a general way the same region and boldly contrasted the one 

 from the other in plumage, constitutes a striking natural phenome- 

 non calling for explanation. 1 



1 Nichols, J. T., American Naturalist. September, 1916; pp. 565-574. 



