228 MR. R. COLLETT ON HYBRID GROUSK. [Apr. 20, 



about one diameter of the eye). In Lagopus they are still shorter, 

 or one diameter and a liaU', in T. tetrix one or two diameters longer 

 than the central reetrices. 



Male and Female. — Besides the markings and size the following 

 differences occur between the two sexes^the tail of the female is 

 nearly square, the side branches of the upper mandible ate more 

 developed, and the comb-like scales of the toes and the ridge of the' 

 eyebrows are consideral)Iy longer in the male Ihnn in the female. 



Measurements. 

 Male. 



Giidbrandsclalen, 7 Dee. 1870. 

 Saltdaleu, XorcUaud, 80 Dec. 1871. 

 Gudbraiidsdaleu, 8 Oct. 1872. 

 Oslerdalen, .o Nov. 1872. 

 Gudbrandsdalen, (?) Nov. 1872. 

 Gudbrandsdalen, 28 Feb. 187.'-!. 

 Hadeland, 27 Dec. 1879. 

 Tolgeu, 3 Nov. 1881. 

 Sande Prgd, 9 Nov. 1881. 

 Roros, 10 Oct. 1882. 



Female. 



Gudbrandsdalen, Jan. 1875. 

 Roros, 7 Oct. 1876. 



It will be seen from these measurements that the male has an 

 average length of 490 millini., about equal to that of the female Tetrao 

 tetrix (but with slightly longer outer tail-feathers). The total 

 length of the female is about 424 millim., being thus considerably 

 less than the male ; it is, however, somewhat larger than the male 

 Lagopus albus. 



t'olouring. 



Of the fourteen specimens of this hybrid at present preserved in 

 the Museum at Christiania, one is a young bird of the year, on 

 which the brown plumage almost entirely remains ; four are young 

 birds changing to winter plumage, the latter being predominant ; 

 finally, are eight in full Avinter plumage, and amongst these are two 

 females. Besides these there is one specimen (a male in winter 

 plumage) exhibited as a skeleton. 



In winter plumage are also the specimens in the Bergen and 

 llpsala Museums. The specimens at Stockholm are likewise, so 

 far as is known, in winter plumage, or in the changing from autumn 

 to winter. A long link in the series is entirely wanting in all 

 these collections, namely — the spring plumage, which is probably 

 unknown ; the summer plumage, which is in all cases known from 



