448 Zoological Society :— 
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 14 inch. 
In the extremely elastic mandible of the Pelican this line of bon 
union is cne-eighth of an inch in length, in the Boatbill one-fourth 
of an inch, in the Adjutant 44 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 rex 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 
Stork, and the Adjutant have each seven pairs of free ribs, the last 
five reaching the sternum ; in Baleniceps and the Adjutant the last 
pair are pelvic; in the White Stork the last two pairs. Until the 
birds are adult, the anterior vertebree of the pelvis are but partly 
united. In the Storks, Herons, Boatbill, and Baleniceps the dorsal 
vertebree continue distinct throughout life ; but in many of the Cranes 
the tendons of the dorsal muscles are ossified, and fasten the bones 
more or less together, and two or three contiguous centra coalesce. 
Among the cervical vertebree of the true Herons and their nearest 
allies, e. g. Ardea, Botaurus, Cancroma, and Baleniceps, there are 
several which have elegant bridges under their upper or cranial end 
for the carotid arteries, which bony bridges are not true heemal 
arches, but are formed by exogenous processes*. In these ver- 
* See Prof. Owen’s article in Orr’s ‘ Circle of the Sciences,’ entitled ‘* Structure 
of the Skeleton and Teeth,” p. 182, fig. 10. iv. 
