Mr. W. K. Parker on the Osteology of Baleniceps rex. 447 
is more than half the length, the upper jaw of the latter being more 
outspread. The degree of arching of the upper jaw is intermediate 
between that of the Boatbill and that of the Stork (Ciconia). The 
gradual rise of the mesial ridge to form the great terminal hook, the 
crescentic notch forming the inferior margin of that beak, and then 
the graceful outward curve of nearly the entire mandibular margin, 
give great elegance to the lateral aspect of the upper jaw. At the 
end of that margin we have the commencement of the great cheek- 
bone, which is nearly two inches long, half an inch broad, and one- 
quarter of an inch thick. ; 
Such a magnitude of the zygomatic arch as this is perfectly unique 
in the class of Birds, being more like the development of thé same 
part in most Mammalia, in the Crocodiles, and in the Turtles. In 
the enormous heads of the larger Hornbills, the cheek-bones are not 
half the size they attain in the Baleniceps. 
The os quadratum, or tympanic bone, which forms so beautiful an 
articular medium between the cranium and lower jaw in birds, is 
strong and well-developed. This bone and the little pterygoid, which 
intervenes between it and the palatines, have very much the character 
of the same bones in the Heron and the Adjutant; but the palatine 
bones themselves, coalescing at the mid-line, and sending downwards 
a strong keel at that part, are exactly intermediate in structure be- 
tween those of the Adjutant and Pelican. These bones and the 
pterygoid at their point of junction are beautifully scooped out to 
receive and glide under the strong beam of bone which forms the base 
of the interorbital septum. 
The great strength of all the bones forming the upper maxillary 
apparatus is in perfect harmony with what is known of the habits of 
the creature. In this respect it has no peer amongst its congeners, and 
no superior except amongst some of the larger Parrots. But the latter 
birds, although they possess the most perfect fronto-maxillary hinge, 
haye nothing in their tympanics, or malar bones, at all comparable 
to those of the Baleniceps. Perhaps the most elegant part of this 
bird’s structure is the hard palate, formed for the most part by the 
coalesced premaxillary bones,—the maxillaries in birds, as in typical - 
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 receivé 
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 haye their 
fullest development in the Green Turtle. The occipital condyle is 
