PERCHES 241

the first the bones of the lower pharynx are separate,
in the second they are united; in the fourth the
ventral fins are posterior ; in the third they are either
missing or placed on the throat. or breast.

Combining these distinctive details, we shall find
that the species of our first division have comb-like
gills; that their premaxilla and upper jaw are
movable; that. they have spinous rays on their
dorsal, anal, and ventral fins; and that their lower
pharynx bones are generally separate. At the head
of these comes the perch (Perca fluviatilis), which is
widely distributed over Europe, Northern Asia, and
Northern America, and which, when full grown, may
attain a length of eighteen inches, though most
familiar to us as about half the size. There is one of
the perch family, Mzcroperca, which when full grown
is only an inch and a half long. The bass (Labrar)
is also in this group, as are the pike-perches (Luczo-
perca), some of which may reach four feet in length.
The sea-perches (Sevranus) run to over seven feet
long in some of their species. Another group consists
of the red mullets, not the grey ones, distinguishable
by their flattened bodies, large thin scales, feeble
teeth, and the two long erectile ‘barbels’ at the
mouth. Next to them come the sea-breams, re-
cognisable at a glance by their flattish, oblong bodies
and large eyes, but chiefly characterised by their
peculiar teeth ; for they have cutting teeth in front
of the jaws or else lateral molars, and sometimes they
have both. To us the most familiar species is the
shad (Pagellus centrodontus) ; but the largest of the
group is Pagrus unicolor, the New Zealand snapper,

Q