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Class AVES. 

 Order RAPTORES. 



Family Vulturidce. 



Genus Lithornis*. 



1550. A portion of the skeleton of the Lithornis vulturinus, Owen. This 

 beautiful fossil includes the sternum nearly entire, the proximal ends of 

 the coracoid bones, a dorsal vertebra, the distal end of the left femur, 

 the proximal end of the corresponding tibia, and a few less characteristic 

 fragments of ribs ; all of which are cemented together by the grey indu- 

 rated clay, which is generally more or less attached to the fossils from the 

 isle of Sheppey, the locality from which the present specimen was obtained. 

 The length of the sternum and the remains of the great intermuscular 

 crest or keel, forbid a reference of the fossil to the Struthious or strictly 

 terrestrial Order, but at the same time do not prove so decidedly, as might 

 be supposed, that the fossil must have belonged to a bird of flight. 

 The Penguins and other Brachyptera, having need of muscular forces 

 to work their wings as paddles while making their way under water, 

 almost equal to those which propel the bird of flight through the air, 

 possess a long sternum, with a well-developed keel. The coracoid bones 

 or posterior clavicles are even less available in this question, as they 

 relate much more closely to the respiratory actions than to the move- 

 ments of the wings, and accordingly are always present and strongly de- 

 veloped, even in such birds as the Apteryx, in which the wings are 

 reduced to their feeblest rudiments. In the present fossil, however, the 

 lateral extent and convexity of the sternal plate, the presence and course 

 of the secondary intermuscular ridges, the commencement of the keel a 

 little way behind the anterior margin of the sternum, all prove the bird 

 to which it belonged to have no affinity with the Brachypterous family of 

 * \idos a stone, opyis a bird. 



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