6l6 MANUAL OF ZOOLOGY. 



the Struthionidtf, and the true Galling, such as the Grouse. 

 Many of the sutures of the skull are persistent, and the brain 

 is very small. There is the lacertilian character that there 

 exists a row of supra-orbital bones. 



Sub-order 2. Columbacd. The second sub -order of the 

 Rasores is that of the Columbacd or Gemitores, comprising the 



Fig. 340. Columbidae. Rock-pigeon (Cohcmba livid). 



Doves and Pigeons, and often raised to the rank of a dis- 

 tinct order under the name of Columba. The Columbacei 

 are separated from the more typical members of the Rasores 

 by being furnished with strong wings, so as to endow them 

 with considerable powers of flight. In place, therefore, of 

 being chiefly ground -birds, they are to a great extent arbo- 

 real in their habits, and in accordance with this the feet 

 are slender, and are well adapted for perching. There are 

 four toes, three in front and one behind, and the former are 

 never united towards their bases by a membrane, though 

 the base of the outer toe is sometimes united to that of the 

 middle toe. The hallux is articulated on the same plane as 

 the other toes, and touches the ground in walking. Lastly, 

 they are all monogamous, and pair for life ; in consequence of 



