390 



ZOOLOGY 



SECT, 



The differences between the two avian sub-classes, the Archasor- 

 nithes and the Neornithes, are, however, of a far more fundamental 

 nature, and as Archaeopteryx, the sole representative of the first of 

 these groups, is a unique form, and perhaps the best example of 

 an undoubted link between two classes Reptiles and Birds it 

 will be convenient to deal with it separately. 



Sub-Class I. Archaeornithes. 



Only two specimens of Archseopteryx have hitherto been found , 

 both in the finely-grained lithographic limestone of Soleiihofen, 



FIG. 996. Archseopteryx lithogrraphica. From the Berlin specimen, c. carpal ; cl. 

 furcula ; co. coraeoid ; h. humerus ; -,-. radius ; sc. scapula ; u. ulna ; I IV, digits. 



