2 28 THE HISTOEY OF CREATION. 



formation of their beaks and feet — are of an exceeedingly 

 uniform organization, in mucti the same way as are the class 

 of insects. The bird form has adapted itself on all sides to 

 the external conditions of existence, without having thereby 

 in any way essentially deviated from the strict hereditary 

 type of its characteristic structure. There are only two 

 smaU groups, the feather-tailed birds (Saururae) and those 

 of the ostrich kind, which differ considerably from the 

 usual type of bird, namely, from those with keel-shaped 

 breasts (Carinatae), and hence the whole class may be divided 

 into three sub-classes. 



The first sub-class, the Reptile-tailed, or Feather-tailed 

 Birds (Saururse), are as yet known only through a single, 

 and that an imperfect, fossil impression, which, however, in 

 being the oldest and also a very peculiar fossil bird, is of 

 great importance. This fossil is the Primseval Griffin, or 

 Archseopteryx lithographica, of which as yet only one speci- 

 men has been found in the lithographic slate at Solenhofen. 

 in the Upper Jura system of Bavaria. This remarkable 

 bird seems on the whole to have been of the size and form 

 of a large raven, especially as regards the legs, which are 

 in a good state of preservation ; head and breast unfortun- 

 ately are wanting. The formation of the wings deviates 

 somewhat from that of other birds, but that of the tail 

 still more so. In all other birds the tail is very short and 

 composed of but few short vertebrae ; the last of these have 

 grown together into a thin, bony plate standing perpen- 

 dicularly, upon which the rudder-feathers of the tail are 

 attached in the form of a fan. The Archseopteryx, however, 

 has a long tail like a lizard, composed of numerous (20) 

 long thin vertebrae, and on every vertebra are attached the 



