Shuff.i.dt : OsTKOLOGv or THK Herodiones. 23!) 



and longer. 'I'he mesial notches are a little dee|)er than the outer ones. 

 A costal border occui)ies about one half of the lateral margin of the 

 bone. The carina extends the entire length of the sternal body, and is 

 wonderfully deep in front, where it is thickened just within its sharp- 

 ened border. 



The lower border is very thin, and the carinal angle is one of 

 about 90°. On the lower or ventral aspect of the sternal body we find 

 the main pectoral muscle-line well marked. 



Either one extends from the outer end of a costal groove back to 

 the distal point of the base of the carina, or nearly there. As in Ta)i- 

 taliis and the Herons the costal grooves decussate and are remarkable 

 for containing transverse, narrow, elongated, low, articulate eminen- 

 ces, which convexities are intended to accommodate similar concavi- 

 ties seen at the sternal ends of the coracoids. Now although the costal 

 grooves of the sternum decussate in all the birds we have just men- 

 tioned, it will be as well to add here, in passing, that the characters 

 of the facets of those grooves and other points about them are 

 quite different in the several groups. There is a small peg-like manu- 

 brium present on the sternum of Plegadis, as is the case in the sterna 

 of its immediate ibine allies, and, as a whole, this bone differs but 

 little among the American genera of these birds. When the elements 

 of the shoulder-girdle are articulated /// situ the long axes of the cora- 

 coids are nearly in the same line with the long axis of the body of the 

 sternum, and the os furcula not only curves well away from the former, 

 but its symphysial portion is far removed from the anterior border of 

 the carina of the latter. The scapulge have their distal apices imme- 

 diately opposite and above the anterior margins of the ilia of the pelvis, 

 and they, as a whole, are well elevated above the osseous parietes of 

 the thorax. 



Os furcula is of the .broad U-shaped variety. It is of nearly uniform 

 thickness and width throughout, with its clavicular limbs much com- 

 pressed laterally, and their free ends very bluntly rounded off. As 

 we near the symphysis below, the surfaces gradually become reversed, 

 so that what was the mesial aspect of either clavicle above, comes to 

 face below as the anterior surface of the symphysis of its own side, as 

 does the outer aspect of the clavicle come to be the posterior sym- 

 physial surface. The merest rudiment of a hypocleidium exists, 

 scarcely worthy of the name. During life the distal end of either 

 clavicle overlaps and is in contact with the top of the head of the 



