330 Proceedings of the Royal Physical Society. 



Grallse ; and show that, like the Secretary Bird and the 

 CATHAETJE, these birds are raptorial forms of various 

 groups only distantly allied to the true Accipitres. Some of 

 the peculiarities of the Osprey's wing may arise from the 

 absence of more than the fifth cubital remex. 



X. The CicoNiiNE Style. — No sharp line of definition is 

 possible between the Gralline style and that under notice. 

 The chief distinction lies in the fact that in most of this 

 group the entire series of feathers next above the Major 

 Coverts has distal overlap. The Tern (Fig. 20) shows this 

 type remarkably well. With slight modifications this would 

 equally well suit the Gulls, the Skuas, the Ibises, the Storks, 

 the Secretary Bird, the Spoonbills, and the Flamingoes. The 

 Ciconiine style is well seen also in the Pernid^. 



XI. The TuBiNARiNE Style. — A progressive increase in 

 the number of feathers showing distal overlap leads us to 

 such types as Leptoptilus, where nearly the whole of the 

 cubital coverts are characterised by distal overlap. Near to 

 these must be placed the Gannets, Plotus, and possibly the 

 Pelicans, the Petrels, the Albatrosses, the Frigate Birds, and, 

 certainly, the CATHAET^. So far as the wing style is 

 concerned, the American Vultures differ entirely from the 

 normal Birds of Prey, and exactly agree with the Petrels, the 

 Albatrosses, the Frigate Birds, and the Adjutants. This last 

 conclusion, derived entirely from the external characters pre- 

 sented by the disposition of the cubital coverts, is exactly in 

 accordance with the deeper-seated morphology as revealed 

 by dissection. This and the other facts of the same nature 

 I have brought forward appear to me to afford strong pre- 

 sumptive evidence that the variations of style which have 

 been noticed in this paper represent a survival of archaic 

 structures whose differentiation dates back to a very remote 

 period in the history of the Sauropsida. It is only because 

 they have long ceased to influence in any way the welfare of 

 the bearers that these various styles of wing coverts have 

 remained unaffected, while other parts of the bird's organism 

 have gradually changed through many stages of evolution. 



In conclusion, I may briefly summarise the facts relating 

 to the various modes of disposition of the Cubital Coverts as 



