BOOM XI.] NATURAL HISTORY. 53 
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 Carapi, merely in having a long dorsal, and no 
anal fin. 
The Morris ( Leptocephalus ) is very peculiar for the ex¬ 
ceeding thinness of its body, which resembles a riband, 
and is nearly as transparent as glass ; its fins are scarcely 
visible, and its intestines occupy merely a very narrow line 
along the lower edge of the body. 
The Launces ( Ammodytes ) have elongated, compressed 
bodies, covered with scales placed in transverse series, and 
the dorsal, caudal and anal fin separate from each other. 
The jaws are acute and extensile : they bury in the sand 
and live on the worms which they find in it. 
The Pipe Fish ( Syngnathidce ) 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 in some 
species are 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 
placed at the base of a prominent muzzle. The ventral fin 
of some of the species of this genus is very large and ex¬ 
panded, whence their name. 
The following fishes differ from all the former by the 
jaws being formed of the maxillary and intermaxillary 
bones united together into one body; and by the pala¬ 
tine arch being connected with the cranium by a suture. 
