Ss om = . . ) reonloate MIS aay = :

in flight, in order to regulate their course during that “igOrous species of |

: : = 5 as S é Ee A

are in number two on each side Fok, nee eels

S of the wschia, and inserted
muscles it is o}

| ht, they also become dorsad of t}
their forces with the elevators, and by this addition of

> arising from the Pp

‘ osterior extremitie
expanded anchylosed vertebre, rom the dis}

1 into the
0SItiIOn o Se i

f these oV1l0us that after the
1€ centre of m;

the act of throwing y

elevators have raised the tail to a certain heig ne

g tion, combine
P the tail by a
that “in these moveme

= ak; power terminate
jerk: Mr. Vigors in his observations on the living animal observes,

seemed to turn as if on a hinge that Was operate a

don by a spring.”
The osseous portions of the mandibles of the Toucan are disposed in a manner adapte
ao a spos “ Manner adapted to combine with
the great bulk o Ose parts a due degree of Strength and remarkable lightness and the bony st t i
9 33, 2 € bony structure is
: Phe external parietes are extremely thin, especially in
a ieee Se ee : :
| yield in a slight degree to moderate pressure, but present considerable
resistance 1f a force is applied for the purpose of crushing the beak. At the points of the mandibles, the
2 , S c 2S,

at other parts, in the upper beak, they
from 1-30th to 1-50th part of an inch, and in

consequently of a most beautiful and delicate kind.

the upper beak : they are elastic, and

r walls are nearly a line in thickness : ar
outer walls < i K are much thinner, varying
the lower beak are from 1-20th to 1-30th of an inch in
thickness.

On making a longitudinal section of the upper mandible, its base is seen to include a conical cavity, about

?
, with the apex directed forwards. The walls of this cone
consist of a most beautiful osseous network, intercepting irregul

two inches in length and one inch in diameter

ar angular spaces, varying in diameter from
half a line to two lines. From the parietes of this cone, a network of bony fibres is continued to the outer

parietes of the mandible, the fibres which immediately support the latter being almost invariably implanted

at right angles to the part in which they are inserted

The whole of the mandible anterior to the cone is occupied with a similar network, the meshes of which
are largest in the centre of the beak in consequence of the union which takes place between different small
fibres as they pass from the circumference inwards. It is remarkable that the principle of the cylinder is
introduced into this elaborate structure: the smallest of the supporting pillars of the mandibles are seen to be
hollow or tubular, when examined with the microscope. The structure is the same in the lower mandible,
but the fibres composing the network are in general stronger than those of the upper mandible.

The medullary membrane lining these cavities appears to have but a small degree of vascularity. Processes
of the membrane, accompanying vessels and nerves, decussate the conical cavity at the base of the beak. The
principal nerves are two branches of the fifth pair, which enter at the as part of ie vont aa and
diverge and ascend as they pass forwards to the end of the bill, giving off branches, which are distributed to
the horny covering, and supply it with sensibility. | | |

The air is admitted to the interior of the upper mandible from a cavity situated anterior Oe orbit, which
communicates at its posterior part with the air-cell continued into ee orbit, and at its anterior Pas ae is
maxillary cavity. The nasal cavity is closed at every part, except at its external and internal apertures, by the
pituitary membrane, and has no communication with the interior g the pee Hen

The organ of smell is confined to the base of the upper ee aria 1 oe ie
odorous particles in inspiration, forms a sigmoid curve in ite eae ; as on a ee
precisely the same perpendicular line as the internal one. It is ae a a a bee aime reat
mandible, where it is raised above the level of the cranrum ; the ae a a foliage.
secure from all injury that might happen to it in the ae oe oe ae st tance ee

The olfactory canal is at first of almost a cylindrical form, and a a is of tite first spongy bone; it
forwards for about half an inch, receiving from we nee TS ee the two other spongy bones :
ten bends downwards and backwards, and is pe - mee and afterwards dilating to form the
from this point it descends vertically to the palate, at fir

s its convexity
ae 5 ‘zontal, and has its convexity
internal teri ifice. The first or outermost spongy bone is almost horizontal, ¢
Internal or posterior orifice.