206 MALACOPTERYGII. — CYPRINID^. 



sort of roof formed by the side of the frontal 

 bone ; and the cornea and iris are divided by 

 transverse bands, which 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 by 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., p. 50. 



