178 



ELEMENTS OF OENITHOLOGT. 



they are called C annate birds. A keel is wanting, or more 

 or less rudimentary only, in the Ostrich, Ehea, Emeu, Casso- 

 wary, and Apteryx, in a single kind of Parrot, a pecmhar Eail- 

 like bird {Notomis), and in the singular Opistkoeomus *, amongst 

 existing birds. 



The lateral part of the sternum which receives the ribs, 

 generally extends forwards on either side into a more or less 

 marked prolongation called the costal process. From the middle 



Fig. WO. 



SiDi! View of Thoeax op Fowl. 



k, ^eel of Bternum ; m, middle Xiphoid process ; i, internal lateral xiphoid 

 process ; e, external lateral xiphoid process ; r, rostrum or manubrium ; 

 0, costal process ; h, hypapophysis from middle of vertebral centrum ; 

 a, appendage from ribs, or uncinate process. 



of the anterior margin of the sternum — which is almost always 

 convex — a single process called the rostrum or manubrium may 

 project forwards and may bifurcate. 



On either side, between this and one of the costal processes, 

 is the coracoid groove. Sometimes (as in the Hoopoe) the 

 median anterior part of the sternum is perforated to receive 

 processes from the bases of the coracoids. Very rarely, «. g. in 



* See ante, p. 94. 



