206 
MALACOPTERYGII. — CYPRINIDiE. 
sort of roof formed by the side of the frontal 
bone; and the cornea and iris are divided by 
transverse bands, vrhich give the fish the ap- 
pearance of having four eyes, whereas in reality 
it has only two. There are certainly two openings 
to each eye, but still, in its essential parts, the 
organ is single ; and whether vision is performed 
by the anterior or posterior opening, the same 
sentient organ is acted on.’’ These remarks are 
confirmed by the observations of a recent natu- 
ralist, Mr. Edwards, who, in his delightful work, 
A Voyage up the Amazon,” thus speaks. One 
curious .species, the Anableps tetrophthalmus^ was 
very common ; it is called bj^ the people, the 
four-eyed fish, and is always seen swimming 
with the nose above the surface of the water, and 
propelling itself by sudden starts. The eye of 
this fish has two pupils, although but one crys- 
talline and one vitreous humour, and but one 
retina. It is the popular belief that, as it swims, 
two of its eyes are adapted to the water, and two 
to the air.”^ 
It adds to the interest of this singular little 
fish, that it, as well as all the other species of this 
group, brings forth its young alive, and in a state 
of considerable advancement. 
2. Cohitina. Here the head is small ; the 
body lengthened, clothed with minute scales, and 
enveloped in a viscous slime. The mouth is very 
small, placed beneath the snout, without teeth, 
but having thickened lips, forming a kind of 
sucker, and furnished with numerous fleshy cirri. 
The gill-openings are small, and there are but 
three gill-rays. There is a small dorsal situated 
^ Voyage, &C .5 p. 50. 
