io Ostcological Studies of the Sub-Family Ardenies. 
immense aperture, permitting a full view of the interior ot the 
brain-case. This individual is not fully matured, however, and 
such may not be the case in the adult Egret. 1 
The olfactory foramen of the Yellow-Crowned Night Heron 
is exceedingly small, while the groove for the passage of the 
nerve from it, in the specimen before me is single. The optic 
foramen, likewise, unites with the interorbital vacuity in 
Nycticorax. 
The posterior orbital wall in the Blue Heron looks forwards, 
downwards and slightly^ outwards ; it presents nothing of particu¬ 
lar interest; the foramen ovale which pierces this wall at its lower 
part in many birds, has in the Herons moved round so as to ap¬ 
pear on direct lateral view, just over the upper edge of the quad¬ 
rate. Upon this aspect the dome of the parietal eminence is well 
seen in profile as is the crotaphyte fossa, with the muscular de¬ 
pression behind it. 
All Herons present three processes for our examination on the 
side of the skull, these are, first, the squamosal process seen im¬ 
mediately above and rather in front of the head of the articulated 
quadrate ; second, the sphenotic process defining the boundary of 
the crotaphyte valley above, and finally, another process just 
beyond the last, formed at the union of the outer angles of the 
frontal and squamosal bones. 
Sutural traces among the bones composing the infraorbital bar 
have almost entirely disappeared ; they can be made out only after 
careful scrutiny in my specimen of the Snowy Heron, which, as I 
have said is not a fully grown bird. In the Blue Heron the line 
of union between the jugal and quadrato-jugal can sometimes be 
faintly recognized in the adult individual. This posterior third 
of the bar is broad and laterally compressed, and the articulation 
with the quadrate a substantial one, by the usual cup and process 
joint. The jugal division of the bone is more slender, though 
also laterally compressed, and the anterior end of the maxillary 
‘This does not hold in the skulls of adult specimens of this Heron, for I find since 
writing the above paragraph, that these foramina in the crania of specimens of A can 
didissima in the collection of Mr. Lucas as well as in those of this species in the U S 
National Museum, the arrangement is quite like I have described it for A herodias 
My thanks are due Mr. Lucas for his c nirtesv in placing at my disposal the material 
to which I refer. From the same source I have been enabled'to compare skulls of 
Bata urns Icntigmosus . B. exilis, Ardea occidentalism A. eg re Ha, several of A candid 
s.’ma. A. virescens , Nycticorax , N. nezvius , and N. violaceus . besides a few skulls and 
skeletons of Herons from foreign lands. Further on in this memoir I will now Li 
traduce some comparisons which this material has enabled me to make 
