960 
the muscles and other soft parts of this region 
of the head. 
The Trigle or Gurnards offer the best ex- 
amples of the “ hard-cheeked Acanthopterygii,” 
which owe their name to the following arrange- 
ment of the above mentioned osseous pieces. 
The first suborbitals are of enormous size, en- 
tirely covering the face, articulating in front with 
the bones of the snout, and posteriorly with the 
preoperculum and twosmaller suborbitals placed 
Fig. 492. 
= 
\ 
ti 
~ 
y Fy, 
7p 
Skeleton of Trigla lyra, showing the bones of the face and the pectoral 1. body, This remarkable resale 
Jin rays. 
at the posterior angle of the orbit. Its articu- 
lation with the preoperculum is accomplished 
by means of an immoveable suture, so that the 
suborbital bones and the preoperculum must 
move together. The upper part of the face, 
moreover, is formed by the immoveable con- 
solidation of the anterior frontals with the an- 
terior extremity of the prenasal bones, which 
expand into a disc, and in some instances of 
the vomer likewise, which is slightly visible 
beneath the skin between the ossa nasi. All 
these bony pieces, as well as those composing 
the upper portion of the cranium, are hard, 
granular, and often armed with spines and 
Ye: - - 
3 . <P, b 
Qa See 
PISCES, ' 
cutting edges, so that few Fishes have their heads 
so well defended against the attacks of their foes. 
The Pleuronectide, or Flat-fishes as they are 
commonly called, offer a most remarkable ex- 
a 
ception to the usual arrangement of the bones 
of the face, which exhibits a want of symmetry 
unparalleled in any other vertebrate animals. 
In this jul oe includes the Turbot, the 
Plaice, the Sole, and others similarly organized, 
the whole trunk of the body is so pe com- 
pressed laterally that such fishes, 
instead of swimming in the usual 
position, lie upon their left sides 
—a circumstance which, z 
to the singular fact that the right 
side is equally coloured both up- — 
on the dorsal and ventral regions, — 
while the opposite is rege ‘ 
white, has given rise to the vul- — 
. gar supposition that the white — 
© surface is the ventral and the co- 
loured the dorsal region of the fish _ 
—an error of which the anatomist — 
is immediately made aware by a 
simple inspection of the skeleton 
(fig.493). But in the construction 
of the head, by a strange apparent 
distortion of the elements com- 
posing the face and cranium, both 
eyes are allowed to be situated 
upon the right or upper surface ¢ 
is entirely due to the suppres- 
sion of those processes and bones on the left 
side of the head which normally constitute the 
orbital cavity, whilst on the right side are: 
permitted to attain a very complete develope- 
ment. The principal frontal bone figs. 436 
437, 1, vol. iii. p. 826-7), which in all Fishes igs 
azygos, occupies its usual situation, but whils 
on the left side it is flat and bounded bya near 
straight margin, on the right side of the mes: 
line it presents as usual the processes which forn 
the roof and posterior boundary of the orbit. Th 
outer margin of the orbital cavity is formed by 
one large bony piece, the representative of t 
sub-orbital chain of bones, (fig. 436, gg 
