Osteological Studies of the Sub-Family Ardeince . 13 
horizontal plate of each maxillary. Anteriorly the palatines 
merge imperceptibly into the premaxillary, rendering it impossi¬ 
ble in the adult Heron to define the exact line of union, their inner 
margins also uniting with each other, in a like manner, as far 
back as the middle point on the inferior border of a maxillo-pala- 
tine. Here abruptly an interval occurs between them, through 
which we may see the hinder half of the latter bones and the lower 
border of the vomer. 
Still more posteriorly the}’ become doubly carinated, the pos¬ 
terior angle of the outer keel being bluntly pointed. At the 
mergence of these keels behind, we find the articular heads for 
the pterygoids, the upper surfaces of both ride the under side of 
the rostrum. 
Now the inner sides of the inner keels of the palatines are 
produced forwards to merge into the vomer in a sharp point be¬ 
yond, thus forming in conjunction with this bone a long doubly 
carinated process, in the median line, opposite the middle thirds 
of the palatine bodies. This process forms a part of the lower 
margin of the vomer, which, as I have said, it really is. The 
median plate of the vomer rises above this, and extends beyond 
it, to project slightly into the interspace between the maxillo-pa- 
latines. The upper margin of this median vomerine plate is lon¬ 
gitudinally split, as it were, and the two thin plates thus formed 
beautifully curl outwards and downwards, on either side, creating 
as they do so a median longitudinal groove on the upper aspect 
of the vomer, over the hinder moiety of which the apex of the 
rostrum hangs, and even, still more posteriorly, meets it in a free 
schindylesial articulation. The middle third of the inner border 
of the upper side of each palatine develops a broad crest that curls 
outwards all along its.summit. On lateral view this crest hides 
the hinder half of the vomer. 
The in axillo-pal a tin es of Ardea herodias are of a highly spongy 
bone tissue throughout. This material imperceptibly merges into 
the more coarsely developed tissue, of a similar character, however, 
that fills the hollow of the superior mandible beyond. Laterally, 
the maxillo-palatines may be said to spring from the anterior hor¬ 
izontal plates of the maxillaries, on either side , such a fact is 
only known to us though from our knowledge of the development 
of these bones in other birds, for we would hardly suspect it here. 
The hinder halves of these bones rise parallel to each other, as 
