No. 3-] THE OSTEOLOGY OF THE PIGEONS. 50 1 



angles with the postero-external angles of the mid-xiphoidal 

 prolongation, thus creating fenestras instead of notches. 



Columbia livia also has a sternum of this pattern (Parker, 

 Newton), but it is not invariably inherited by the various 

 forms of domestic pigeons, as in the skeleton of an " Arch- 

 angel " before me I find that the internal-xiphoidal processes 

 do not unite with the mid-xiphoidal piece. ^ 



Nearly all of the Colutnbidcs show a distinct, mesial, forward- 

 projecting process on the anterior border of the sternum, which, 

 in most species, is quite as conspicuous as the manubrium below 

 it. It is present in both Zenaidura and Ectopistes.' 



Zenaidura has slenderer scapulae than we see in the Pas- 

 senger pigeon ; their posterior moieties not being evidently 

 truncated, and they are narrower and more pointed. 



The characters seen in the vertebral column, pelvis, ribs, 

 etc., of Ectopistes are essentially repeated with great exactness 

 in such a species as Engyptila albifrons, and the same may be 

 fairly said for the sternum and shoulder-girdle. An interest- 

 ing point, however, presents itself in the two skeletons of 

 Ejigyptila at hand, for in the male bird the sternum is widely 

 two-notched upon either side of the carina, — the female having 

 had a sternum the internal xiphoidal processes of which unite 

 behind with the mid-xiphoidal piece and thus create fenestrae, 

 as in Zenaidura. The union is very complete and firm and is 

 important as going to show that the "fenestration," or "notch- 

 ing," of the xiphoidal portion of the sternum in pigeons counts 

 as nothing for a character. From this it will be seen that it 

 varies even in the same species. 



As figured by the Newtons, the sternum of Patagicenas 

 caribbcsa possesses the anterior pair of notches, but it is only 

 upon the left side posteriorly that a very small foramen is 

 seen to exist. In other words, the internal xiphoidal processes 

 have almost merged with the mid-xiphoidal prolongation in 

 this species {Phil. Trans., 1869, PI. XXXIII, Fig. 173). 



1 Mr. Schollick, of the United States Museum, kindly furnished the skeleton of 

 this domestic pigeon. 



2 See memoir on the Accipitrcs (in MSS.), and the description of a somewhat 

 similar process on the sterna of the several species of Falco. 



