418 



ZOOLOGY 



SECT. 



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

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

 nature ; and as Archseopteryx, 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 oi Archceopteryx lithographica have hitherto 

 been found, both in the finely-grained lithographic limestone of 



^?*!&^ 





Fig. 1056.— Archseopteryx Utbographica, From the Berlin specimen, f. carpal; d, 

 furcula ; m. coracoid ; h. humerus ; r. radius ; sc, scapula ; u. ulna ; 1— IV, digits, 



