52 
NATURAL HISTORY. [UPPER FLOOR. 
and at others both are pale rosy white. When both the 
sides are brown, the fins are interrupted over the forehead, 
and the eyes are placed one on each side of the head of the 
fish. These fish have been divided into several genera, 
according to the length of the dorsal, and the distinctness 
of the pectoral fins. Some, as the Zebra Sole ( Plagusia ), 
are entirely without pectoral fins, and have the anal, 
caudal, and dorsal united into one. 
The third family of this division are the Suckers (Cy- 
clopteridce), so called from the pectoral fins being united 
together into a disc, by which they attach themselves to 
marine bodies. Their skin is slimy and naked, or with 
hard grains embedded in it. The pectoral fins are large. 
They live in shallow water, near coasts, and swim with 
great vivacity. 
The Remorae ( Echeneisidce ) form the last family of the 
soft-finned, subbrachian fishes. They are known by the 
top of the head being flattened, and furnished with trans¬ 
verse series of cartilaginous plates, (somewhat similar 
to the plates under the toes of the Gecko,) by which these 
fish attach themselves to ships, rocks, and marine bodies. 
The second group of soft-finned fish consists of those 
which have no ventral fins ( Apoaa ). The first family of 
these are the Eels (Murcenidce) , which have a long slender 
body, covered with small scales sunk into a thick slimy 
skin. Their gill-flaps are small, surrounded by the gill- 
rays, and covered with the skin, leaving merely a small 
tubular opening for the emission of the water. This struc¬ 
ture enables the fish to live a long time out of water. 
They have been divided into several genera, according to 
the teeth and the proportion of the fins. In most of the 
species, the dorsal and anal fins are long and united toge¬ 
ther ; in others they are short and quite separate ( Morin - 
guci); and in some they are entirely wanting. In 
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 
