22 Osteological Studies of the Sub-Family Ardeinee. 
the Yellow-Crowned Night Heron, we find a still longer and better 
developed pair on the eighteenth in this form, and yet another 
free pair on the nineteenth. These latter have epipleural append¬ 
ages, although they do not meet the sternum by costal ribs 
below. This gives three pairs of free ribs to Nycticorax ; four 
pairs as in other Herons that meet true sternal ribs ; and a pair 
from the pelvis, to which is attached false floating ribs, or a pair 
of those that articulate with the hinder borders of the preceding 
sternal pair proper. 
In Ardea herodias and 
A. candidissi??ia , the second 
pair of free ribs support epi¬ 
pleural appendages, low 
down on the bone. 
For the moment I 
must now be permitted to 
defer our further conside¬ 
ration of the vertebral col¬ 
umn, . f il the sternum and 
pectoral arch have been 
disposed o ' After that I 
will return to the examina¬ 
tion of the pelvis and coc¬ 
cygeal vertebrae, upon the 
completion of which the 
appendicular skeleton will 
finally engage our atten¬ 
tion. 
Of the Sternum : — 
(Figs. 7, 8, 9, 31 and 32). 
Upon direct pectoral view, 
the sternum of Ardea hero¬ 
dias is seen to be broader 
in front than it is behind ; 
this is due to the projection 
from the former end, on either side of the large costal processes 
or otherwise the bone on this aspect would have a pretty regular 
quadrilateral figure. 
The xiphoid extremity is doubly notched,—a broad triangu¬ 
lar indentation deeply entering upon either side. This gives rise 
Fig. 7. The Sternum of Ardea herodias , viewed 
from below. Life size from nature. 
