y.

With the fingers, or tweezers, grasp the cut edge of the skin of the
back and with the scalpel carefully separate it from the flesh as far as
the middle line of the back from the head to the tail. Remove the
exposed flesh to the backbone. With the knife, shears or fine tooth saw,
split the head lengthwise a little to one side of the middle, leaving
somewhat more than half. Do not sever the skin of the body where it
comes to a point between the gills, and use great care when removing the
flesh from this portion.

You now have a trifle more than one-half the fish to work on. With the
scissors cut through the ribs and remove the backbone with some of the
flesh. Be careful when cutting through the backbone at the tail not to
cut through the skin below. Going back to the head, remove the remaining
flesh, and with the curved scissors and scalpel cut away all the
cartilage possible from the head; the more the better so long as the
skin is not injured. If enough of the cartilage can be removed to expose
the muscles of the cheek from the inside, cut them away, taking out the
eye; otherwise it will be necessary to work from the outside of the skin
through the eye opening, and this must be done very carefully or the
skin of the cheek may be broken. With most fishes it is possible to
remove all the cartilage from the head, and this should be done to
prevent shrinkage. If the mouth is to be open, do not cut away its
lining or much of the tongue behind. The tongue is to be split
perpendicularly lengthwise and about one-third of it removed. When the
head has been thoroughly cleaned, remove the remaining flesh from the
body with the skin scraper or scalpel.

The ventral fin which is uppermost as the fish lies on its side and is
not to show, should be carefully cut off outside the skin. Do not cut
off the ventral fin on the side which is to be displayed. Do not scrape
away the silvery lining of the skin if this can be avoided. Some of it
will come off. Cut away the bases of all the fins and the tail inside
with the curved scissors and scrape away all flesh, working close to the
fingers so as not to stretch the skin. Tie the vent inside with thread.
Unless the fish is quite small, the skin of the lower jaw must be
loosened with the knife or scalpel and the muscles cut away. The
adipose, or small fleshy fin on the back near the tail of such fishes as
the trout, must be carefully opened from the inside of the skin with a
small-blade