POSITION OF LEGS OF BIRDS DURING FLIGHT. 141 



good many notes dealing with various birds, which are perhaps 

 sufficiently interesting to bring together here. These were com- 

 mitted to paper in various distant regions as the incidents came 

 before me. They were finally summarized and collected in South 

 Africa before I had read Mr. Finn's paper. I am therefore 

 pleased to find that I not only corroborate his main contention 

 that the position of the feet may vary, but carry it further, 

 showing that (in the case of some of the Gulls at least) the feet 

 may be moved not only from the anterior to the posterior posi- 

 tion, but also in the opposite direction. 



It seems to me that in steady continuous flight the tibiae of 

 all birds must necessarily occupy a horizontal position pointing 

 directly backward. The position of the metatarsi will depend 

 upon three conditions — that is to say, its length, the shape, 

 structure, and point of juncture of the leg with the body, and the 

 use which the bird makes of it in catching its prey or otherwise. 

 If the metatarsus is very long, as in the Stilts and Herons, the 

 only possible position for it is the horizontal pointing straight 

 backward, where it is probably of considerable use in assisting 

 the short tail. In numerous species again, as in the Albatrosses, 

 the metatarsus is just long enough to cause the feet to project 

 slightly further backward than the ends of the central rectrices. 

 The birds appear at first sight as if their central tail-feathers 

 were somewhat elongated, and no doubt the rudder-like use in 

 flight, of legs of this particular length, is similar to that of the 

 elongated central tail-feathers, which are so common in many 

 birds of strong or unusual powers of flight, such as the Tropic 

 Birds, Skuas, some Bee-eaters and Goatsuckers, and the males 

 of some Honeysuckers. 



In birds with still shorter, but yet comparatively long, meta- 

 tarsi, the legs are carried in the same position, but the feet lie, 

 according to their length of leg, at some point beneath the rectrices. 

 Where the metatarsi are still shorter the position for the feet is 

 near the vent. As examples of the former condition I may quote 

 the larger Gulls, such as Larus glaucescens of Bering's Sea, of 

 the latter many of the Auks. Here again the legs are still of con- 

 siderable assistance to the flying bird, since they may be separated 

 so as to increase the width of the tail ; they may be placed both 

 together at one side, or they may be allowed to partially drop 



