1S67.] PROF. HUXLEY ON THE CLASSIFICATION OF BIRDS. 459 

 -f-5. The ALECTOROMORPHiE, 



The rostrum may be slender and depressed, or high and arched. 

 Oval, flattened basipterygoid facets, sessile upon the basisphe- 

 noidal rostrum and articulating with corresponding surfaces upon 

 the pterygoids, are always present. The maxillo-palatines are 

 always lamellar, but vary greatly in size, being sometimes very 

 small. 



Tlie palatine bones are relatively long and narrow, with obsolete 

 internal laminse, and rounded-off postero-external angles. 



The angle of the mandible is produced into a strong upcurved 

 process. 



The sternum has either one or more, generally two, very deep 

 posterior notches on each side ; when there are two, the external late- 

 ral processes thus marked out are much shorter than the internal. 



The feet vary considerably in the relative size and in the position 

 of the hallux, and in the development of spurs. They are never 

 completely, or even largely, webbed. The ratio of the phalanges of 

 the front toes is as in the preceding groups. 



According to Nitzsch the feathers have aftershafts, and the ptery- 

 losis is remarkably uniform in all the genera except the Pteroclidce, 

 a family which, in this and some other respects, but not in cranial 

 characters, approaches the Pigeons. 



Except in Pterocles, the oil-gland is surmounted by a circlet of 

 feathers. 



The inferior larynx is always devoid of intrinsic muscles. 



Excluding the Pigeons and the TinamidcB, this group corresponds 

 with the Gallinse of authors, and contains the families Turnicidce, 

 Fhasianidce, Ptej'oclidce, MegapodidcB, and Cracidce. 



The TiirnicidcB approach the Charadriomorphse, the Fteroclidce 

 the Peristeromorphse ; while the CracidcB have relations with the 

 birds of prey on the one hand, and with Palamedea and the other 

 Chenomorphse on the other. 



— 6. The Peristeromorph^. 



The rostrum is swollen at the tip, and provided at the base with 

 a tumid membranous space, in which the nostrils open. 



The skull is provided with narrow, but prominent, basipterygoid 

 facets. 



The maxillo-palatines are elongated and spongy. 



The angle of the mandible is not produced and recurved. 



The sternum has two posterior notches, the inner pair of which 

 may be converted into foramina. The external lateral processes 

 thus formed are, as in the Alectoromorphse, much shorter than the 

 internal lateral processes. 



The hallux is on a level with the rest of the toes, and its meta- 

 tarsal is peculiarly twisted. The anterior toes are not at all webbed. 

 The ratio of the phalanges is as in the preceding groups. 



The feathers have no aftershaft (? Dldus), and the oil-gland is 

 devoid of a circlet of feathers. 



