COMMON REMORA. 281 



oval, adhesive disk, on the top of the head, by means of 

 which they are able to attach themselves firmly to the sur- 

 face of other fishes, or the bottoms of vessels ; but whether 

 for protection or conveyance, or both, is a question which has 

 not been satisfactorily ascertained. 



The Greeks and Romans were well acquainted with the 

 Mediterranean species, which is the fish under present con- 

 sideration. 



The length of the head, from the end of the upper jaw, 

 which is much the shortest, to the end of the operculum, 

 is nearly one-fifth of the whole length of the fish ; the depth 

 of the body about one-seventh of the whole length : the 

 form of the head is flattened, very much depressed ; the 

 body about the middle nearly round in form, the posterior 

 half compressed : the mouth is wide ; the opening nearly 

 horizontal, with two bands of minute teeth in the elongated 

 lower jaw, a single band on the upper jaw, with others on 

 the tongue and vomer, all curving inwards : the eye placed 

 about half-way between the point of the upper jaw and the 

 rounded end of the operculum ; the gill-aperture very large ; 

 the adhesive disk in this species contains seventeen or eigh- 

 teen transverse laminae, divided by a longitudinal mesial 

 ridge ; the disk commences just behind and above the upper 

 lip, and extends nearly as far back as the line of the ends 

 of the pectoral fin-rays : all the fins are covered with a dense 

 membrane, which imparts to them the consistence of leather ; 

 the pectoral fins are rather small and rounded ; the ventrals 

 narrow, very close together, the inner ray of each attached 

 to the central line of the belly by a membrane ; the dorsal 

 and anal fins are both placed behind the mid-length of the 

 fish, beginning and ending on the same plane ; the end of 

 the caudal rays crescent-shaped. 



VOL. II. U 



