THE GEOLOGICAL KECOliD 231 



tifully preserved in the fme-gi'aiued beds of lithographic stone. 

 The accompanying ilhistration is from an exact drawing of this 

 specimen (Eig. TO), in order to render more distinct the details 

 very faintly shown in the original. To the anatomist every 

 bone or fragment of a bone is recognisable ; while the mimis- 

 takable feathers, and the foot with the increasing number of 

 joints from the inner to the outer toe, are sufficient to show 

 that it is a true bird, notwithstanding its curiously elongated 

 tail feathered on each side. In this specimen there is no sign 

 of the head ; but fortunately another specimen has recently 

 been found, in which the skull is well preserved, and which 

 shows that the beak was armed with teeth (Fig. 71). Later 

 on, in the Cretaceous for- 

 mation of Kansas, U.S.A., 

 some well-preserved aquatic 

 birds have been found. 

 One is of large size (about 

 1 feet high), something like 

 a diver, but with flat 

 breastbone, and therefore 



probably with rudimentary Fig. 71.— Skull of Archwopteryx 

 wings; another, much ^ siemensi, showing Teeth. 



_ From the lithographic stone (Upper Jurassic) 



smaller, has long wing- of Bavaria. Xat. size. Original in the 



1 1 11111 Berlin Museum. (B.]\r. Guide.) 



bones and a deeply keeled 



sternum. The bonv tail of 



these is not much longer than in living birds, but in both the 



beaks are toothed. 



The main reason for the extreme rarity of bird-remains in 

 the Mesozoic era is, that being so light in body and plumage 

 they could very rarely be presei'\Td. Those tliat died in or 

 on the margins of rivers or lakes, or wdiich fell into the water, 

 would be at once devoured bv the fishes or the aquatic or aerial 

 reptiles which seem to have swanned everywhere. 



