15® Mr. Thomas’s anatomical Description , &c. 
at its broadest diameter ; therefore, upon their contracting, the 
axis of vision will be shortened, and the retina brought nearer 
to the crystalline lens ; consequently, the eye will be better 
fitted for seeing objects at a distance. In birds, there is placed 
at the posterior part of the eye, a muscular process, called by 
Haller, pecten avium, by others, marsupium : this answers 
the same purposes as these processes, the arrangement of its 
fibres only differing. In the chameleon, and also in many fishes, 
a similar structure is found, calculated to produce the same ef- 
fects ; and probably something of the same nature may be seen 
in the eyes of many other animals, which has hitherto escaped 
observation. 
As it is impossible for language to convey a just idea of the 
relative situation of these processes, I have subjoined sketches, 
shewing them in three different points of view: the parts repre- 
sented are of the natural size. 
Plate X. Fig. 1, Represents a longitudinal section of the globe 
of the eye ; the vitreous humor is removed, and the choroid coat 
detached and brought forward : a bristle is introduced between 
the two processes and the sclerotic coat. 
Fig. 2, Represents the internal and posterior portion of the 
sclerotic coat ; the foramen for the passage of the optic nerve in 
the centre ; and the four processes arising at equal distances 
from it. 
Fig. 3, Represents an outside view of the processes, losing 
themselves in the choroid coat : portions of folded paper are 
placed under each, to render them more distinct. 
Fig. 4. A portion of the jejunum inverted, to shew the fold- 
ings of its internal membrane. 
