in flight, in order to regulate their course during

> arising from tl
expanded anchylosed vertebre. From the dig

that vigorous species of |
1e posterior e
sition of the

: ocomotion.
are in number two on each side

These muscles
xtremities of the ase

hia, and inserted into ¢]
les it is Obvious that
orsad of the centre
rminate the ac
living animal observes, tl
as Operated on by
The osseous portions of the mand

1e

se muse after the proper

ght, they also become d

addition of power te
jerk: Mr. Vigors in his observations on the

tors have raised the tail to a certain hei : :
eleva ee of motion, combine
their forces with the elevators, and by this

t of throwing up the tail by a
lates

j In these movements the tail
seemed to turn as if on a hinge that w

a spring.”
ibles of the Toucan

are disposed in a manner ad
egree of strength

and remarkable lig
The external parietes

apted to combine with
the great bulk of those parts a due d

htness, and the bony structure js
consequently of a most beautiful and

delicate kind. are extremely thin, especially in
the upper beak : they are elastic, and yield in a sl rate pressure, but present consid
- At the points of the mandibl

oper beak, they are muc
» and in the lower beak are

ight degree to mode

le purpose of crushing the beak
outer walls are nearly a line in thickness

from 1-30th to 1-50th part of an inch
thickness.

erable
resistance if a force is applied for tl es, the
h thinner, varying

from 1-20th to 1-30th of

; at other parts, in the uy

an inch in
On making a longitudinal section of the upper mandible, its base is se

en to include a conical cavity, about
two inches in length and one inch in diameter,

with the apex directed forwards. The walls of this cone
varying in diameter from
, a network of bony fibres is continued
immediately support the latter being almost inv
at right angles to the part in which they are inserted.

The whole of the mandible anterior to ¢]

consist of a most beautiful osseous network, intercepting irregular angular spaces,
half a line to two lines. From the parietes of this cone to the outer
parietes of the mandible, the fibres which

ariably implanted

1€ cone is occupied with a similar network, the mes]

1es of which
are largest in the centre of the beak in conseque

nce 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 sup

porting pillars of the mandibles are seen to be
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.

hollow or tubular, when examined with the microscope.

ini se cavities ars S legree of vascularity. Processes
The medullary membrane lining these cavities appears to have but a ee a é : oe -
1 vessels rves sussate the coni vity at the base of the beak. 1e
of the membrane, accompanying vessels and nerves, decussate the conical ca J ob
j th pair, which enter at the lower part of the conical cavity, and
principal nerves are two branches of the fifth pair, whic a lca
: ss forwards to the end of the bill, giving off branches, which are distributed to
diverge and ascend as they pass forwards to , giving
‘ covering, and supply it with sensibility. mares
ze 2 a. Samy ; ; # ‘ terior of the upper mandible from a cavity situated anterior to the orbit, which
The air is admitted to the interior o é iis yeti OE a
j i ] ; s anterior part with the
: : j air-c 1ed into the orbit, and at its an
icates at its posterior part with the air-cell contint
ee een e i very part, except at its external and internal apertures, by the
maxillary cavity. The nasal cavity is closed at every part, ex | . , 7
, . icati 7] interior of the mandible.
itui é ‘ as no communication with the in — oa
toe se of tl yper jaw. The canal, which is traversed by the air and
The organ of smell is confined to the base of the Up] eal dinette “Hie eae ee
eee: . Vonnord Curve ai the went ; }
ae : forms a sigmoid curve in -
" Be eh nepiration, i It is si 1 at the posterior surface of the upper
; i i ¢ t is situated a pos
: : ‘ular line as the internal one. tt ecaete
precisely the same perpendicular fice id. dondeqtcetiwaisec ebeaetenemn
I dibk ] it 7 above the level of the cranium ; the orifice 1s conseq 1 pie:
oo oe, where It Is : : rating dense or interwoven foliage.
: it i t of penetrating
Me a ht happen to it in the act aan ioe
secure from all injury that might hay ae te a oe es
Tl If Ss il is at first of almost a cylindrical form, and about ne pilié-fese soGnoanenee
——— ; . Seen le first s 5 ;
a. : iving from the mesial aspect the projection o pong
forwards for about half an inch, receiving from Imit the projections of the two other spongy bones :
: is di dmit the pr ee
ee ‘kwards, and is dilated to a ee ean
ee aed and backwards, late, at first contracted, and afterwards dilating ic fo
from this point it descends vertically to the palate, < bone is almost horizontal, and has its convexity
. st or rmost spongy
i i . he first or outermost g
internal or posterior orifice. T

rn
1 ey
Nenanee ne

FIEIIIEET

 
  
   
  
   
  
  
   
  
  
   
    
  
    
   
    
  
  
 
  
 
 
 
  
  
 
  
  
 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 
 
 

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