On British Fossil Birds. 381 



Ithaginis geoffroyi. 



There are a pair of these birds in the collection. Mr. Pratt 

 procured a clutch of seven eggs from a nest on the ground 

 under the brushwood in the forest, 13,500 feet above the sea. 

 It is a very common bird, and alights and probably roosts in 

 the pine-trees. The eggs vary in size from 2*05 inches by 1*3 

 to 1'85 by 1*32 inch; in colour they resemble handsome 

 eggs of Tetrao tetrijc. 



XXXIV. — On British Fossil Birds, By R. Lydekker, B.A. 



Owing to the absence in the British Isles of strata corre- 

 sponding to the freshwater Miocene beds of France in Gers, 

 Allier, and the Auvergne, in which well-preserved bird-re- 

 mains are of such common occurrence, the list of fossil birds 

 found in this country is comparatively small. The total num- 

 ber of species recorded, indeed, is only slightly over 60 ; and 

 since some 45 of these belong to existing species, of which the 

 remains are found in caverns, the fens, and other superficial 

 deposits, the list of extinct forms sufficiently well described 

 to be admitted as valid ones falls short of 20. It must not, 

 however, on this account be presumed that the subject of 

 British Fossil Birds is one of only slight interest or im- 

 portance. Indeed, the very reverse of this is the case, for 

 while the existing species the remains of Avhich occur in the 

 superficial deposits afford some interesting information in 

 regard to geographical distribution, the extinct species found 

 in the London Clay belong either to types totally unknown 

 elsewhere, or represented abroad by kindred but distinct 

 genera. Again, the little that is yet known of the extinct 

 birds of the Upper Eocene beds of Hordwell, in Hampshire, 

 indicates that we have there an avian fauna which contains 

 types at present unknown in the corresponding strata of the 

 Paris basin. Unfortunately the bird-remains from these 

 Hordwell beds are comparatively rare, are frequently very 

 imperfect, and are distributed through several museums, so 

 that the means of comparison and the consequent determi- 

 SER. VI. — VOL. III. 2d 



