214 THE OCEAN. 



bright azure; nor the three or four pretty little 

 Rudder-fishes (Perca saltatn'x, Linn.), which have 

 been following and accompanying us for several 

 days past. These are amusing little creatures. They 

 are about six inches long, yellowish brown, with 

 pale spots: they keep close to the stern, in the angle 

 formed by the rudder and the counter of the ship, 

 the "dead water'' as it is called by seamen. Hence 

 they occasionally dart out after any little atom of 

 floating or sinking substance which promises to be 

 eatable, and then, having either seized or rejected it, 

 scuttle back again to their corner, remaining there 

 day and night without rest. Nor can we do more 

 than glance at the Sucking-fishes (Echeneis), that 

 are swimming around, or have attached themselves 

 to the side of the rudder by means of the singular 

 oval disk on the head. As this organ is of singular 

 construction, so its use in the economy of the animal 

 is involved in entire obscurity. The theory of the 

 fish being a very slow swimmer, and needing to be 

 carried along by others, must have been formed by 

 persons who never had an opportunity of seeing the 

 Eemora alive. I have seen many, and could detect 

 no inferiority in their powers of swimming to a 

 young Shark of the same size, which they much re- 

 semble in general appearance and motion, when in 

 the water. There seems to be a perfect vacuum 

 formed by the adhesion of the disk, and the external 

 pressure, when under water, is of course great. As 

 the mouth opens upon the upper surface of the muz- 

 zle, owing to the projection of the lower jaw, it 

 is possible that this habit may be connected with 



