NOM^EIDS AND MACKERELS 



2741 



vies thoracic in position. Both in this genus and Elacate the shape of the caudal fin 

 is subject to considerable change with age; the middle portion in the young being 

 produced into a long filament, which gradually shortens until a rounded margin is 

 produced. At the time of the full development of the fish the corners of the tail 

 have, however, grown out, so as to convert the rounded fin into an emarginate or 

 forked one. Of the two most common members of the genus Echeneis remora, 

 which is the one represented in our illustration, is comparatively small, growing 

 only to a length of about eight inches; whereas E. naucratcs, characterized by the 



SUCKING FISHES. 



(Two-thirds natural size.) 



slenderness of its form, may reach a yard in length. Sucking fishes are inhabitants 

 of nearly all seas, and in a fossil state are found in the lower Eocene deposits of 

 Switzerland. 



Sucking fishes are commonly found attached to the bodies of sharks, although 

 they may affix themselves either to turtles or ships; and as they are carried by 

 their involuntary hosts through a much greater extent of water than their limited 

 powers of swimming would admit of their traversing by themselves, they naturally 

 obtain a much greater supply of food than would otherwise be possible. The 

 erection of the plates constituting the sucker produces a series of vacua, by means 

 of which the adherence is effected; and so strong is the adhesion that it is very 

 difficult to remove one of these fishes except by sliding it along the surface to which 



