] 18 THE ECHENEIS. 



gular fanning with its filmy pectoral fins. This habit 

 seemed to me at first useless and unaccountable, but 

 on consideration I have little doubt that its purpose 

 is to produce a more free and rapid change of the 

 surrounding water ; and that it is one of those com- 

 pensatory actions that we frequently meet with in 

 physiology, and that are so interesting. 



In the tropical seas I have had many occasions 

 of witnessing the actions of a still more singular 

 Sucking-fish, the Echeneis. The notion put forth 

 in books, that this fish, being a very slow swimmer, 

 needs to be carried along by others, is simply absurh, 

 and must have been formed by those who never saw 

 the fish alive. It is in no wise inferior, in swiftness or 

 power, to fishes of the same size with which it asso' 

 ciates, the Sharks for instance to which it so com- 

 monly affixes itself. The Echeneis bears a very 

 close resemblance, when seen in the water, to a 

 young Shark. It is fond of attaching itself to a 

 grown Shark, usually choosing a spot just behind 

 the pectoral fin, but it as commonly adheres to 

 the rudder or to the bottom of a ship. I have 

 thought that the singular habit may be connected 

 with its manner of taking food ; especially as the 

 month, owing to the projection of the lower jaw, opens 

 on the upper side of the muzzle. Now when the co- 

 ronal disk is affixed to any foreign body, the lips are 

 made to touch the latter also. We know that there 

 are multitudes of minute animals, such as Crustacea, 

 Cirripedia, &c. that live parasitioally on the bodies of 

 marine animals, and on foreign objects habitually 

 submerged. If the Echeneis feeds on these, there is 



