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fish, having avery backward position and often inferior development. 
The mid-line of this highly arched hard palate is occupied by a par- 
tially open canal for a large venous sinus, which receives on either 
side numerous vein-grooves at right angles. This gives a beautiful 
leaf-like appearance to this structure. 
Just inside the margin of the posterior angle on the under surface 
of this great upper jaw the bone is cut away, as it were, to receive 
the coronoid portion of the lower jaw. This excavated part is conti- 
nuous anteriorly with a deep groove, margined internally by a sharp 
ridge, which gradually rises inside the palate to pass forwards in a 
sigmoid manner to the base of the great terminal beak, where it 
meets the submesial groove on the upper surface of the jaws. In the 
Common Heron these palatine submarginal lines exist, being covered 
in the horny sheath by sharp ridges. These ridges have their 
fullest development in the Green Turtle. The occipital condyle is 
hemispherical and large ; and the base of the skull has a very ex- 
quisite structure, which deserves full description, as it exceeds any- 
thing we have seen in birds, the Heron making the nearest approach 
to the Baleniceps in this particular. Many other birds, however, 
show traces of this peculiar structure. The lower jaw is exceed- 
ingly strong and thick, as compared with that of the Adjutant. 
Less elliptical and more triangular than that of the Boatbill, it 
has, nevertheless, many of the characters of the latter. Its tip is 
curiously emarginate, as is also the tip of the upper jaw—the bony 
basis of the great hooked beak. The traces of suture between the 
dentary and other elements of the mandible, which are persistent in 
the Boatbill, Adjutant, and most other birds, are all filled up with 
bony matter, as is the case in the Parrot tribe, in the Hornbills, and 
in the Toucans. The anterior part of the mandible passes within the 
maxilla, the edge of its horny sheath fitting between the marginal and 
submarginal ridges of the latter. Where the upper jaw begins to 
narrow towards its angle, there the mandible rises high (its height 
or depth here being 14 inch), and it is rounded, rough, and strong. 
It then lowers again, and becomes rapidly broader, to form the deep 
and wide articular cavities for the tympanic bone above, and the 
broad flat angular processes behind and below. 
Each ramus of this great inelastic mandible is united to its fellow 
at the symphysis by complete bony union to the extent of 13 inch. 
In the extremely elastic mandible of the Pelican this line of bony 
union is one-eighth of an inch in length, in the Boatbill one-fourth 
of an inch, in the Adjutant 43 inches, and in the Hornbill, Buceros 
bicornis, more than 7 inches. 
In the Boatbill and Grey Heron there are twenty-three separate 
vertebree between the head and the pelvis; in Baleniceps rea and 
the Adjutant twenty-one, and in the White Stork twenty. 
In the Boatbill there are nine pairs of free ribs. The last, or pelvic, 
does not reach the sternum, nor do the first four, so that there are 
four true dorsal ribs. In the Heron there are eight pairs; the an- 
terior three and the last (which is pelvic) do not reach the sternum,— 
here there are only four true dorsals. The Baleniceps, the White 
