422 PROF. HUXLEY ON THE CLASSIFICATION OF BIRDS. [Apr. 1 1, 



8. The pubes are free ; but the ischia unite beneath the urosacral * 

 vertebrae. 



9. The hallux is absent ; but the second, third, and fourth digits 

 are complete. 



10. There are only thirty-two precaudal vertebrse. 



11. The feathers are devoid of an aftershaft. 



The Malayo-Australian genera Casuarius and DromtEus are mem- 

 bers of a third group, which may be defined as follows : — 



1. The maxillary processes of the palatines are short, as in Rhea. 



Undei" view of the skull oi Dro7n(ms nova-hollandio'. From a specimen in the 

 Museimi of the Royal College of Surgeons. 



The letters have the same signification as in the preceding figures. 



* I term " urosacral " those caudal vertebrae which unite with one another and 

 with antecedent vertebrai to form the " sacrum " of a bird. 



