1887.J PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 139 



TETEAOXOIDE^. 



97(107). Lagopus ridgwayi Stejx. 194. 



Eesideiit. Numerous on both islands, 



A large series of additional specimens secured by Mr. Grebuitzki 

 confirms the distinctness of this species. 



ACCIPITROIDE^. 



98 (108). Falco rusticolus Lin. 203. 



The Gray Gyrfalcon is only a winter visitor to the islands, and is not 

 uncommon. 



In the Nouveaux Memoires de la Societe Imperiale des Xaturalistes 

 de Moscou, Tome XV, livr. 3 (1885), p. 09, Mr. M. Menzbier has pub- 

 lished a posthumous memoir by the late Dr. N. A. Severzow, in which 

 the latter describes a new Gyrfalcon as Hierofalco grebnitzl'ii, from a 

 single specimen collected at Bering Island by Mr. Grebuitzki. 



The diagnosis of this alleged new species is given as follows: 



" Cauda valde apice rotunda, rectricibus externis li" brevioribusquam 



medife; remigibus 3>2>1>4>5 Adultus colore H. gyrfalconi 



sen. simillimus, S€d subcaudalibus solo vexillo externo trausversim 

 fasciato, areis nuchalibus duabus, circumscripte albo-fulvesceutibus, 

 quarum plumse anguste uigro raarginatffi." 



Having seven specimens of the alleged new form from Bering Island 

 and Kamtschatka (my friend Captain Hunter having recently favored 

 me with two specimens, adult and young, from the latter country) 

 against Severzow's one specimen, I may, perhaps, be able to throw ad- 

 ditional light on the question, although I do not consider my material 

 quite sufficient yet to settle it entirely to my own satisfaction. 



In regard to the alleged plastic differences between F. grebnifzlii and 

 its congeners I can state without hesitation that they are of no value 

 whatsoever. In none of my specimens is the tail so strongly rounded 

 as in the one described by Dr. Severzow, the maximum distance be- 

 tween outer and middle tail-feathers being only 1 inch (No. 10995:>4), while 

 in most of the specimens it is less than one-half inch, against li inches 

 in Severzow's specimen. He lays considerable stress upon the fact that 

 in the type of F. grebnitzkii the third primary is longer than the second,* 

 while in the allied species the second is longer than the third, but this is 

 purely an individual variation, for in all the specimens before me the 

 second primary is decidedly longer than the third, the normal condition 

 in the Gyrfalcons. 



The specimens before me show a nearly complete intergradation be- 

 tween the dark upper head with light margins to the feathers and the 

 white head with narrow dark shal't-streaks, so that the coloration of 

 the head is quite unserviceable as a character for separating the Kamt- 



* It seems tbatiu his specimeu the third primary is longer thau the second in one 

 wing and equal to it in the other (see op. c'f., p. 70.) 



