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fluence the mode of flight, as instanced by the Swift, Swallow, and 

 Martin, the Tits and the Wagtails, the Starlings and Partridges. 

 It will probably be found, when this matter is more fully investi- 

 gated, tbat all soaring birds, and those that remain stationary in 

 the air for a short time, have hollow humeri, as the Falcon and Sky- 

 lark. It will be interesting also to observe the influence of climate 

 as regards the presence of air in the bones. 



If we look to the form and length of the bones of the wing, how 

 different are they in birds possessing almost equal powers of flight ! 

 Take this example before me, the wing of the Swift and of the Marsh 

 Harrier. The length of the bones of the former is : — humerus, 

 4 lines ; cubitus, 8 lines ; metacarpus, 8 lines ; phalanges, 4 lines ; 

 total 2 inches ; longest primary feather, 5^ inches. Total length of 

 wing, 7jf inches. 



In the Marsh Harrier the humerus is 4 inches in length ; cubitus, 

 4-2- inches ; metacarpus, 2i inches ; phalanges, 1 inch ; and pollex, 

 f of an inch ; the longest primary feather, 12 inches ; the length of 

 the bones, 13 inches. Total length of wing, 23 inches. 



The difference in the comparative length of the wing-bones in 

 these birds is very remarkable, and numerous instances of a similar 

 kind might be adduced ; but I am obliged to limit myself to a few 

 examples. 



From the above investigation I have come to the subjoined con- 

 clusions : — 



1st. That in the majority of British birds no air-cavities connected 

 with the lungs are present in the bones. 



2ndly. That the presence of air in the bones is not necessary for 

 swift and long-continued flight, as instanced especially by the Gulls, 

 Snipes, Swallows and Martins. 



3rdly. That in no bird that I have examined was air found in 

 the bones of the extremities beyond the humeri and femora. 



Dr. Crisp exhibited a nest he had found in June last in the eastern 

 part of Suffolk, which he believed to be that of the Great Grey 

 Shrike (Lanius excubitor). It was placed in a thick hawthorn fence, 

 about 12 feet from the ground, upon a large forked branch. It was 

 composed chiefly of dried grass and a little moss on the exterior, 

 the lining of short grass ; no horsehair nor clay was present ; the 

 form ratber shallow, and the size about that of the Missel Thrush 

 (T. viscivorus), the diameter 6 inches, the greatest depth from the 

 rim 4 inches ; from the top of the dome next described to the bottom 

 of the nest 9o inches. It was closely domed over with twigs, vary- 

 ing in length from 8 to 1 2 inches, a small hole being left in the rim 

 for the entrance of the bird. The nest resembled that of the Magpie 

 (P. caudata) in miniature, but, as before stated, no clay entered 

 into its composition. 



Dr. Crisp was inclined to tbink that this was the deserted and 

 unfinished nest of the Grey Shrike, as two birds of the colour of a 

 Jay were seen about the spot early in the spring by a person well 



