1867.] PROF. HUXLEY ON THE CLASSIFICATION OF BIRDS. 423 



2. The maxillo-palatines are flat, imperforate plates, which unite 

 solidly with the praemaxillae and the vomer. 



3. The vomer is long, and articulates behind with the palatine 

 and pterygoid bones. 



4. The prefrontal processes are large and well ossified. 



5. The bodies of the proper sacral vertebrae do not unite with the 

 pubes or ischia ; and the bodies of the urosacral vertebrae are very 

 large, thick, and well ossified. 



6. The sternum is long and escutcheon-shaped, at first widening 

 and then coming to a point behind. 



7. The humerus is not nearly half so long as the distance between 

 the pectoral arch and the ilium, and is much shorter than the sca- 

 pula. The antebrachium -is not more than half as long as tlie hu- 

 merus. Only one digit, the median, is complete and bears a claw. 



8. Neither the pubes nor the ischia unite in the middle line of 

 the body. 



0. The hallux is absent, but the other digits are complete. 



10. There are thirty-five precaudal vertebrae. 



1 1 . The feathers have aftershafts as long as the principal shafts. 



The extinct Binornis of New Zealand differs from the other Ra- 

 titae, and thus represents a fourth group, in exhibiting : — 



1 . A skull with high arched beak and projecting occipital con- 

 dyle. 



2. Flat, imperforate maxillo-palatine plates, which unite solidly 

 with the praemaxillae and probably with the vomer, as in Bromceiis. 



3. A Dromyeine pelvis. 



4. A broad sternum with two posterior notches. 



5. A very rudimentary pectoral arch, which appears to have pos- 

 sessed no glenoidal cavity for the articulation of the humerus. 



6. Three toes, the hallux being absent. 



7. The feathers have an aftershaft*. 



Lastly, the remarkable living New Zealand genus Apteryx repre- 

 sents a fifth division, having : — 



1 . The palatines short and broad, and uniting by an oblique suture 

 with the expanded maxillo-palatines, which are flat, imperforate 

 plates uniting with the premaxillaries and the vomer. 



2. The vomer long and uniting with the palatines and pterygoids 

 posteriorly. 



3. The prefrontal processes very large and spongy. 



4. The bodies of the proper sacral vertebrae not united with the 

 ischia or pubes ; the urosacrals large and well ossified. 



5. The sternum broad and with two posterior excavations. 



6. The humerus longer than the scapula, and extending for about 

 half the distance between the pectoral arch and the ilium. The 

 antebrachium about half the length of the humerus, and the manus 

 possessing but one claw. 



7. Neither the pubes nor the ischia united in the niiddlo line of 



* See Dallas, Proceedings of the Zoological Society, 1805. 



