48 
NATURAL HISTORY. [UPPER FLOOR. 
one genus ( Synbranchus), the gill-flaps only open by a 
single aperture in the under side of the neck. The 
Ophidium ( Ophidium ) is very like the Eel, but its body 
is more compressed, and the gill-flap, formed as in the 
generality of fish, has a wide opening beneath. The rays 
of the dorsal fin are simple. 
The Gymnoti ( Gymnotidce ) have the gill-flap covered 
with a membrane,like the Eels; but this membrane is open 
behind the pectoral fins. These fishes have no dorsal, but a 
long anal fin. In some the body is eel-shaped and naked, 
as in the electric Gymnotus ( Gymnotus electricus). In the 
Carapi ( Carapi) the body is compressed and covered with 
scales. The Gymnarchi ( Gymnarchi ) differ from the Ca¬ 
rapi, merely in having a long dorsal, and no anal fin. The 
Morris ( Leptocephalus ) is very peculiar for the exceeding 
thinness of its body, which resembles a riband, and is nearly 
as transparent as glass ; its fins are scarcely visible, and its 
intestines occupy a very narrow line along the lower edge* 
of the body. 
The Launces ( Ammodytes ) have elongated, compressed 
bodies, covered with scales placed in oblique transverse 
series, and the dorsal, caudal, and anal fins separate from 
each other. The jaws are acute and extensile : they bury 
themselves in the sand, and live on the worms which they 
find in it. 
The Pipe Fish (Syn gnat hides) form the next group. 
They have the jaws, and the fibrous bony skeleton of 
other fishes, but their gills are divided into little tufts, 
placed by pairs on the bony branchial arches, instead of 
being formed of regular pectinated plates. Their body is 
also covered with shields, which give it an angular appear¬ 
ance. In the true Pipe Fish ( Syngnathus) the mouth is 
situated at the end of a tubular beak. The eggs, which 
are always carried by the male fish, are in some spe¬ 
cies hatched in a sort of bag, formed by a puffing up 
of the skin under the abdomen, or at the base of the tail, 
which splits asunder to allow the escape of the young. 
Many of the species are straight, but some contract after 
death, so as to form a grotesque resemblance to a horse in 
miniature, whence they are called Sea Horses ( Hippocampi ). 
The Pegasi ( Pegasus ) differ from them by the mouth being 
