202 Proceedings of the Royal Physical Society. 



tracts which are now soibmerged have formerly been dry land — some of these 

 changes having taken place in very recent geological times. And the same 

 conclusions are frequently suggested by geological evidence. Thus there can 

 be little doubt that Europe in Tertiary times extended further into the 

 Northern Ocean than it does now. And it is quite possible that in the Meso- 

 zoic and PaliBozoic eras considerable land-areas may likewise have appeared 

 here and there in those northern regions which are at present under water. 

 There is hardly any portion, indeed, of the continental plateau which is now 

 submerged that may not have been land at some time or other. But after 

 making all allowance for such possibilities, the geological evidence, so far as it 

 goes, nevertheless leads to the conclusion that upon the whole a wider expanse 

 of the primeval continental plateau has come to the surface since Tertiary 

 times than was ever exposed during any former period of the world's histoi-y. 



XX. Notes on Crested Birds of Prey. By J. G. GooDCHiLD, 

 Esq., F.Z.S., M.B.O.U. [Plate X.] 



(Read 18th December 1889.) 



In determining what style of plumage would best suit the 

 particular requirements of Birds of Prey, ]S"ature would appear 

 to have taken into consideration what would wear best, and 

 would at the same time make the smallest demands upon the 

 vital energies of the wearers, rather than what would form the 

 most striking kind of adornment. It is more than doubtful 

 whether the majority of these birds would gain any very 

 direct advantage by either assimilative or protective colora- 

 tion ; and even sexual selection, which has played so 

 important a part in the development of adornment amongst 

 other birds, appears hardly to have affected many of the 

 Birds of Prey at all. Everything else seems to have been 

 subordinated to the particular requirements connected with 

 their several predatory modes of life. The colours through- 

 out the entire group are sober combinations of white with 

 various browns, greys, and buffs, which are disposed in 

 simple patterns, consisting of various combinations of stripes, 

 bars, and spots. 



Almost the only feature about these birds that has any 

 claim to be regarded as decorative consists in the elongation 

 of one or the other of the various groups of feathers whose 

 bases are situated on the head or the parts adjoining. 

 Several types of such elongated feathers exist ; and in the 



