112 Recent Literature. |_Jan. 



tion and other conditions. Some thirty or more forms — species and 

 races — are now recognized, and to facilitate their discussion a synopsis 

 of them, in the form of a key, with their distribution, is given in a footnote. 

 The group, with its peculiar geographical distribution and its several 

 rather distinct types of coloration offers a tempting subject for specula- 

 tion, which our author has utilized in a most interesting and fairly con- 

 servative way, emphasizing at the same time the great dearth of material 

 at present available for study in relation to many of the forms. As Dr. 

 Stejneger says: "All these questions are of the utmost importance and 

 interest, but with the present utterly inadequate material at the disposi- 

 tion of the ornithologist, it is scarcely possible to more than lift a corner 

 of the veil. Until the true inter-relations of these birds have been ascer- 

 tained; until the distribution of the forms thus established has been actu- 

 ally mapped in considerable detail; and until the results thus gained have 

 been verified by correlation with the physiographic features of the country 

 in the field by competent observers; until then we shall have nothing but 

 guesses ... I need only mention that no less than nine different forms of 

 palaearctic dippers have been described during the last two years, the 

 scant material upon which these are mostly founded being distributed 

 among six different museums." Nor is the case of the dippers an isolated 

 instance; it is merely a forcible illustration of the condition of such prob- 

 lems in general, not only in the palaearctic field, but over the greater part 

 of the world's surface. — J. A. A. 



Scott 'On the Probable Origin of Certain Birds." — The birds here 

 referred to, nine in number, are all included in the 'Hypothetical List' 

 of the A. O. U. Check-List, and are the following: Tringa cooperi Baird, 

 Acanthis brewsteri Ridgw., Emberiza townsendii Aud., Helminlhophaga 

 lawrencei Herrick, H. leucobronchialis Brewster, Sylvia carbonata Aud., 

 Sylvia montana Wilson, Muscicapa minuta Wilson. Two of them, H. 

 lawrencei and H. leucobronchialis, are discussed at length, the other seven 

 being disposed of in few words, his conclusion respecting them being that 

 "the law of parsimony [whatever that may be] compels me to consider 

 these forms as mutations (which were not perpetuated) from species still 

 existing which I have, in most cases, been able to indicate." Of four of 

 them the unique type specimen is still extant; the other three are known 

 only from the works of Wilson and Audubon. 



In accounting for the origin of all of these nine forms he resorts to 

 de Vries's hypothesis of mutants. In considering the two forms of Hel- 

 minthophila — lawrencei and leucobronchialis — he emphatically rejects the 

 current hypothesis of hybridity to account for their origin, for, he says, 

 "though hybrids do occur among wild birds, they can be considered at 



J On the probable Origin of Certain Birds. By William E. D. Scott. Science, 

 N. S., Vol. XXII, pp. 271-282, Sept. 1, 1905. 



