240 MR. R. COLLETT ON HYBRID GROUSE. [Apr. 20, 



also leaves and twigs of different plants, procured principally on the 

 marshes, and occasionally (like Arctostaphylos alpina) from the true 

 alpine district ; likewise from various berries, and occasionally from 

 birch-catkins. Several of these articles of nourishment form the 

 food of Blackgame ; nevertheless it is certain that most of them 

 come from marshy places, from which it must be assumed that its 

 diet most resembles that of the Willow-Grouse. 



Skeleton. 



In a skeleton of a male from Saltdalen (Nordland) the measure- 

 ments are as follows : — 



n^illim. 



Length of the skull (bill included) 63 



Greatest breadth of the skull 28 



Length of scapula 78 



Length of humerus 73 



Length of radius 65 



Length of ulna 71 



Length of os coracoideum , 55 



Length of metacarpus ii 39 



Length of the two phalanges of digitus ii 31 



Length of furcula (to the edge of the plate). ... 66 



Length of sternum 120 



Greatest height of crista sterni 34 



Length of pelvis (to the first caudal vertebra) . . 73 



Greatest breadth of pelvis (across ossaischii). ... 57 



Length of femur 76 



Length of tiljia 21 



Length of tarsus 45 



Length of middle toe (claw not included) 45 



As the skeletons of the two parents, Lagopus albus and Tetrao 

 tetrix, resemble each other so nearly that, apart from their difference 

 cf size, it would be difficult to find out tlie most trifling characteristic, 

 this hybrid hardly has one distinctive feature in the structure of its 

 skeleton beyond its difference in size. 



Christiania, March 1886. 



EXPLANATION OF THE PLATES. 



Plate XXI. 



Hybrid between Lagopus alhus and Tetrao tetrix. 



Fig. 1. Male in winter dress. 

 Fig. 2. Female in winter dress. 



Plate XXII. 



Hybrid between Lagopus albus and Tdrao tetrix. 



Fig. 1. Young male in early autumn dress. 

 Fig. 2. Young male in late autumn dress. 



