372 
SPINY-FINNED GR 0 UP 
may be considered certain that this fish is the survivor of the ancestral type from 
which its more specialised relatives have been evolved. The body of the sucking- 
fishes is elongate and pyriform; the eyes are lateral, or directed downwards and 
outwards; and the cleft of the mouth is deep. Villiform teeth are present, not 
only in the jaws and on the bones of the palate, but generally also on the tongue; 
the scales are minute; and there is no air-bladder. The second dorsal and anal 
fins are elongated, and the pelvics thoracic in position. Both in this genus and 
Elticate 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 
sucking-fishes (§ nat. size). 
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 8 inches ; whereas E. 
naucrates, characterised by the 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 
