ROOM XI.] NATURAL HISTORY. 45 
Percoid Fish, by the bones of the face being very large, so 
as to cover the cheeks. Some of these have the pectoral 
fins so large, that the fish can support themselves for some 
time in the air, and are therefore called Flying Gurnards 
( Dactyloptera ). 
Cases 1 and 2. The Scienoid and the Sparoid Fish 
differ from the Perches, in the palate being without teeth. 
Some of these, as the Sargi ( Sargus ), have large teeth on 
the side of the jaw (Chrysophrys and 'Dentex). 
The Msenoid Fish differ from those of the two former 
families, by the jaw's being protractile and retractile. 
The Chsetodons ( Chcetodontince ) are known by their com¬ 
pressed form, and by their dorsal, and often their other fins 
being covered with scales like the rest of the body. The 
teeth are usually very small and numerous, resembling 
bristles, from whence the name. The common Chsetodons 
( Chcetodon ) have their opercular bones finely ciliated, while 
the horny Chsetodons have the lower part of the operculum 
ending in a large spine. These fish are very numerous on 
the rocky shores of the seas of warm climates. They are 
generally beautifully and variously coloured, and good for 
food; many are rejected from prejudice. 
The Sea Bream ( Brama ) has many of the characters of 
the Chsetodons, except that the palate is not toothed. 
The Scomberoid Fish {Scomberidee') have a smooth skin 
covered with a multitude of small scales, and a large caudal 
fin. They are much used as food, and afford great employ¬ 
ment to the fishermen. The Mackrel ( Scomber ) has two 
dorsal fins: the hinder rays of the posterior are separated 
from each other, forming, as it were, a series of small fins, as 
in the common Mackrel (Scomber scombus ). Some of the 
species have a ridge of cartilaginous spines on the side of the 
tail. The Sword Fish ( Xiphias ) is very like the Tunny, 
but the front part of its upper jaw is produced into a long 
beak, with which it attacks the larger sea animals. It swims 
with excessive rapidity, and its flesh is much praised. The 
common Sword Fish (Xiphias gladius ) has no ventral fins. 
The Flying Sword Fhh. {Notistium) has distinct ventral fins, 
and the dorsal very high and long, which enables it to swim 
with such velocity that it can drive its beak through the 
stout oak planking of a ship. A fine specimen of this fish 
is in a Case over the Fire-place, and by the side of it a 
