628 SCIENTIFIC RECORD FOR 1882. 



it is the second digit, and curiously enough (3) in one form — the Pas- 

 serine genus Cholornis — the fourth toe is aborted. 



The customary number of phahxuges is "2, 3, 4, 5, in the respect- 

 ive digits, counting from -within outwards," but this type is deviated 

 from in a number of instances. (1) Certain members of a family whose 

 representatives generally develop the normal structure may deviate 

 therefrom, as do the genera Cypselus and Panyptila among the Swifts 

 or Cypselids, which have 2, 3, 3, 3 phalanges. (2) The Pteroclids 

 and typical Caprimulgids develop only 2, 3, 4, 4, phalanges, '' the 

 fourth digit being one short of the normal number of phalanges"; and 

 (3) in the Procellariids, " the number of joints in the hallux is reduced 

 to one," the digital formula being 1, 3, 4, 5, except in Pelecanoides, 

 where the hallux is "quite absent." 



Interbreeding of Birds. 



Mr. Henry Seebohm thought that "the inter-breeding of birds sup- 

 posed to be specifically distinct is a subject which has been much neg- 

 lected by ornithologists," and has called attention to certain facts or 

 alleged facts bearing on the subject. "Two forms which are appa- 

 rently very distinct, as Corvus corone and C. comix or Carduelis major 

 and C. caniceps, are nevertheless found to be only sub-specifically dis- 

 tinct — a complete series of examples from one extreme form to the 

 other in each case being obtainable. They are produced by interbreed- 

 ing with each other as well as with the intermediate forms. The 

 Shrikes (Lanius) and Dippers [Cinclus) offer other illustrations, as do 

 likewise the Nuthatches {Sitta). "The case of the Crows and the 

 Goldfinches, where the extreme forms interbreed, is exceptional ; but 

 the cases where the individuals of each valley in4:erbreed with their im- 

 mediate neighbors, and where the range is great enough to make the 

 sum of a series of small differences show a large difference in the ex- 

 tremes, is by no means uncommon." 



For the details respecting the species enumerated reference must be 

 had to Mr. Seebohm's article in the " Ibis" (4 s., v. 6, pp. 546-550). The 

 facts he brings forward are susceptible of another explanation, but the 

 subject discussed is of sufficient interest to demand attention. 



New North American Birds. 



A number of new forms of birds, previously unknown to the Korth 

 American fauna, were added thereto during 1882. Most of these are 

 the results of Mr. Eidgway's investigations, and have been described as 

 "subspecies" of species in the "Proceedings of the United States 

 National Museum," v. 4, pp. 374-379 ; and v. 5, pp. 9-15, 114, 344. The 

 additions by Mr. Ridgway and others are as follows, the numbers ap- 

 pended indicating the position in his catalogue : 



1. Hylocichla fuscescens salicola R.—Eocky Mountains (2a). 



