PEEFACE. 



TaE remains of Birds constitute almost the smallest group of verte- 

 brate fossils known * ; indeed, it is only within the last thirty-five 

 years that any considerable number have been recorded. 



The first truly ancestral and generalized type of Bird obtained 

 by the British Museum was the reno^med Archaopteryx from the 

 Lithograjihic Stone (Upper Jurassic) of Bavaria, discovered in 1861; 

 a bird with 20 elongated caudal vertebrae, having throughout its 

 length feathers arranged in pairs attached to each vertebra, and 

 three free digits in the manus armed with claws. A second 

 specimen, made known 20 years later (preserved in the Berlin 

 Museum), shows the neck and the skuD, the mandibles being armed 

 with small conical enamelled teeth fixed in distinct sockets. 



In 1870 Prof. 0. C. Marsh discovered in the Chalk of Kansas, 

 N. America, a large flightless aquatic bird, probably resembling the 

 Loons and Grebes in structure. This bird, which he named Hesper- 

 ornis regalis, had its jaws armed with teeth implanted in grooves ; a 

 second bird described by him in 1872, and named Ichthi/oniis victor, 

 was a flying bird with biconcave vcrtcbra% and teeth implanted in 

 distinct sockets in the jaws. The characters of these birds indicate 

 undoubtedly a great antiquity for the class, and point most clearly 

 to their close relationship with the Reptilia, from which they were 

 probably evolved in Triassic times. 



* The class Amphibia is the smallest section. 



