138 THE STORY OF THE EARTH. 



bones in the forearm instead of two. Omosaurus 

 is a large land saurian found at Swindon. The 

 common shells of the clay include Ostrea delta 



1 virgula t Lingula avails and Ammonites 

 bipl 



The Solenhofen slate of Bavaria makes known 

 numerous insects and other forms of terrestrial 

 life of this period, including the oldest known bird. 



77/6' Oldest Known Bird, 



A bird is known by its feathers; though there 

 is no reason why the covering to the skin should 

 not be as variable in this group of animals as 

 among reptiles or mammals. It is therefore re- 

 markable that the oldest known bird named 

 Archaopteryx has feathers as well developed as in 

 the existing representatives of the class and simi- 

 larly arranged. It is found in the lithographic 

 slate of Solenhofen in Bavaria, which is of about 

 the age of the Kimeridge clay, in the Upper part 



Of the Oolites. The animal is an elegant slender 

 bird which is chietly remarkable for showing teeth 

 in the jaws. About twelve, short and conical, oc- 

 cur on each side in the upper jaw. The skull is 



about two inches long, shaped like the skull in 

 many existing birds, with a circle of sclerotic bones 

 defending the eye. 



I 1 eck and back are each about 2 : ,' inches 



e is a slender rat-like tail, ^( more 



than twenty elongated vertebra-, which is 0\ inches 

 long. The fore limbs are as well developed as the 



hind limbs. But they differ from existing birds in 



the bones of the metacarpus not being blended 



ether, and in the three- digits terminating m 



,c,\ s. 1 he number of the phalanges in the 



