io Ostcological Studies of the Subfamily Ardeincz. 
The vertebral column may be seen in part through the aper¬ 
tures afforded by the acetabulum and ischiadic foramen upon this 
lateral view. Except at its sacral dilatation, the neural canal as 
it passes through the vertebrae of the pelvis is small ; it will be 
remembered that we found it quite so in the dorsal region also. 
My specimen of the pelvis, taken from the skeleton of Ardea 
candidissima (a bird of the year), although thoroughly herodine 
in all of its salient points, it still differs in some of its minor details, 
from the same bone in Ardea herodias. A careful count shows 
that an equal number of vertebrae are anchylosed together to 
form the central mass for the support of the pelvic arch,—four¬ 
teen in each case, i. <?., the twenty-fourth to the thirty-seventh 
inclusive. This obtains also in the Yellow-Crowned Night 
Heron, and in both these birds the rim of the pelvic basin departs 
from and arrives at identically the same segments as described for 
Ardea. 
In A. candidissima , the ilia do not overreach the twenty - 
fourth vertebra, although otherwise these bones are comparatively 
longer and narrower than in A. herodias. A greater number of 
in ter-apophysial foramina pierce in double rows the middle area 
in this heron ; these, however, may be obliterated in older birds. 
Nycticorax also possesses a true heron’s pelvis, and so far as 
this bone is concerned the differences between it and the pelvis of 
Ardea herodias are of so trivial a nature as scarcely to be noticed 
on first sight. The principal ones are these : in Nycticorax the 
gluteal ridges and outer angles are not nearly so prominent ; a 
greater number of inter-apophysial foramina exist upon the dorsal 
aspect ; the last vertebra, the thirty-eighth of the spinal column, 
anchyloses with the sacrum, although it projects entirely beyond 
the pelvis, this one corresponding to the first of the free coccygeal 
series in A. herodias ; the hinder ends of the isehia are cut squarely 
across and do not apparently project beyond the ilia ; and finally, 
the obturator foramen is more nearly entire. 
I find seven freely articulated coccygeal vertebras in Ardea hero¬ 
dias and a pygostyle. A. candidissima shows but six, and the 
pygostyle, but it may be possible that one of these vertebrae has 
by some accident been lost in my specimen. We saw above in 
Nycticorax , how, in that heron the first one of the series anchy¬ 
losed with the pelvis, both by its centrum and by the antero- 
external angles of its diapophyses. 
