British Fossil Birds. 401 



two humeri of a bird which was recognized by their describer 

 as closely allied to the French Pelagornis. Although he 

 quotes M. Milne-Edwards's figure of the type of the latter, 

 Sir R. Owen totally ignores the observations of that zoolo- 

 gist as to the Steganopodous affinities of Pelagornis, and 

 proceeds to compare Argillornis with Diomedea, in conse- 

 quence of which he misinterprets some of the features of the 

 humerus in his figures. From an examination of these 

 humeri (which are now in the British Museum) the present 

 writer is convinced, not only of their close affinity with 

 Pelagornis, but also of their relationship to Sula. It is, 

 indeed, at first sight somewhat difficult to point out how the 

 type of humerus in Argillornis can be generically distin- 

 guished from that of Pelagornis; although, from the cha- 

 racters of the undermentioned ulna, it is probable that the 

 one dififered from the other in the presence of a distinct ole- 

 cranal fossa. A fragment of the shaft of a similar humerus 

 had been previously described in 1854 by the late Dr. Bower- 

 bank as Lithornis emuinus ; the generic name is, however, 

 preoccupied by the above-mentioned Accipitrine genus, and 

 since the specific one is inapplicable to a short-legged volant 

 bird it has been rejected in favour of theOwenian terra. In 

 1866 Prof. H. G. Seeley, when describing a somewhat similar 

 fragment of bone, which he identified with the so-called 

 Lithornis emuinus, proposed to replace the name Lithornis by 

 Megalornis, but the latter term had been employed in 1840 

 by Dr. Gray in a different sense. The fragment of bone in 

 question was regarded by its describer as part of the tibia of a 

 Ratite bird; but Sir R. Owen pointed out a serious objection 

 to this view, and it is probable that the specimen is really part 

 of the distal extremity of the left humerus of Argillornis. 



The British Museum possesses part of the proximal extre- 

 mity of a left ulna from Sheppey, which from its size and 

 general character is evidently referable to the genus under 

 consideration. This bone, which has a well-developed 

 olecranon, closely resembles the ulna of the Gannet, and is 

 utterly unlike that of the Albatross ; it may, however, be 

 generically distinguished from that of Sula by the absence 



