398 Mr. R. Lydekker on 



Finally, nothing can at present be said as to the affinities 

 of the u]3per part of a tibia from Hordwell in the Wood- 

 wardian Museum at Cambridge, briefly described, without a 

 figure, as Macrornis tanaupus. Mention must also be made 

 here of a tarso-metatarsus from Hordwell, noticed on p. 557 

 of Owen^s " British Fossil Mammals and Birds/ This 

 specimen was formerly in the collection of Mr. J. W. Flower, 

 but was subsequently transferred to the Museum at Oxford. 

 There, however, according to information kindly supplied to 

 the writer by Prof. A. H. Green, it cannot now be found, 

 although it may be stowed away in certain cases not yet 

 unpacked. According to Sir R. Owen, this bone closely 

 resembles a tarso-metatarsus from the Paris basin figured in 

 Cuvier^s ' Ossemens Fossiles,' vol. iii. pi. Ixxii. fig. 2 ; and it 

 doubtless indicates a species difl'erent from any of those 

 noticed above from the Hordwell beds. 



IV. Birds of the Lower Eocene. 



A long gap occurs between the horizon of the Hordwell 

 beds and that of the London Clay, which is the next deposit 

 in descending order where bird-remains are met with. Here, 

 as might be supposed, not only are all the genera extinct, 

 but many of them depart very widely from existing types, 

 and at least some of them indicate extinct families ; although 

 all the Carinate genera appear referable to existing ordinal 

 groups. It is in the Lower Eocene that in Europe we first 

 meet with remains of birds that may apparently be referred to 

 the E-atitse. The majority of the Lower Eocene bird-remains 

 have been obtained from the Isle of Sheppey ; but unfortu- 

 nately, both here and elsewhere, they generally consist of 

 isolated bones (which are frequently imperfect), so that there 

 is in many cases a certain amount of difficulty and uncer- 

 tainty in determining the number of species we have to deal 

 with. 



Accipitres. — The earliest evidence of the occurrence of 

 remains of birds from the London Clay was afi'orded by a 

 specimen from Sheppey which came into the possession of 

 John Hunter before the year 1793, and is now in the Museum 



I 



