2IO NATURAL SCIENCE. Sept., 



foot of an ordinary perching bird ; so for the present we may let the 

 question rest. 



II. — By Frank Finn. 



There are some points in Mr. Lucas's interesting paper on this 

 subject on which I should like to offer a few remarks. 



In the first place, Mr. Lucas considers that the deterioration of 

 flight in birds which take to water is the greatest objection to the 

 derivation of flying birds from aquatic ancestors. This would 

 indeed be a powerful argument were such deterioration universal ; 

 but it is not. A surface-swimming bird may on the one hand take to 

 diving, and then is pretty certain to deteriorate in flying power. The 

 Anatidae form a good example of this, the semi-terrestrial Sheldrakes 

 having larger and broader wings than the more aquatic typical 

 ducks, while these again are better winged than the diving-ducks 

 (Fuligulinae) ; and the spine-tailed ducks (Erismaturina;), which seem 

 to be as aquatic as Grebes, have the smallest wings of all, except 

 the Loggerhead, which is an outlying degenerate form with no very 

 great diving power. 



But, on the other hand, a surface-swimming bird may take to 

 flying more than ever. It can hardly be doubted that the Gulls are 

 better flyers than even their Plover-like ancestor, though the Alcidai 

 have, as Mr. Lucas points out, degenerated. 



Similarly, the Steganopodes exhibit, in the Pelicans, surface- 

 swimming forms v/ith powerful wings, and the wing-power is increased 

 in the Gannets, Tropic birds, and especially the Frigate birds ; while 

 the diving Cormorants have their wings reduced, and the extinct great 

 Shag [Phalacrocorax pevspicillatiis) was apparently becoming flightless 

 when its fate overtook it. 



The Phalaropes present us with an interesting instance of water- 

 birds of recent evolution ; they are as yet only surface-swimmers, 

 with wings not noticeably diff"erent from those of ordinary littoral 

 sandpipers, and may in the future develop either way. 



Thus, the transition is rather, in the first place, from land to 

 water, and the bird may either become more aerial or more aquatic 

 in consequence of the change of habit. 



Similarly, birds which are markedly terrestrial are either good 

 flyers, as Plovers and Sand-grouse, or exhibit a tendency to degenera- 

 tion in flight just as marked as that of some aquatic birds. Instances 

 of this are, of course, the Ratites, and such Carinates as Ocydromus 

 and Stringops. The Gallinae and Crypturi are also usually poor flyers, 

 though none are yet quite flightless. Stringops, be it observed, must 

 have lost its arboreal habits before it became flightless, and we find 

 that the genera of Parrots which are probably most nearly allied to 

 it, Pezoporiis and Geopsittaciis, are already terrestrial. Arboreal habits 

 tend to preserve an average type of wing, flightlessness being 

 obviously disadvantageous in such case, and also marked length of 



