Mr. W. K. Parker on the Osteology of Balseniceps 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 the 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 Balceniceps. 



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, 

 have nothing in their tympanies, or malar bones, at all comparable 

 to those of the Balceniceps. 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 a very 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 



