LUMP SUCKER. 369 



rays, Avhich sometimes from abrasion of the hard skin appear 

 externally, and have been considered as bearing some resem- 

 blance to an anterior dorsal fin. Behind this central ridge, 

 and over the last third portion of the curve of the dorsal line, 

 is the true dorsal fin, the length of the base of which is about 

 equal to the length of the longest of its rays ; the pectoral 

 fins descend low on the sides, and passing forwards enclose 

 the adhesive apparatus which extends anteriorly to the edge 

 of the membrane connecting the branchiostegous rays, and 

 backwards as far in a vertical line as the posterior angle of 

 the operculum : the union of the ventral fins complete the 

 single disk of the only species of this genus that inhabits our 

 seas. The anal fin is under or opposed to the dorsal, and of 

 nearly the same size and shape ; the tail moderate. 

 The fin-ravs in number are 



tt 



D. 11 : P. 20 : A. 9 : C. 10. 



Each of the rays with a row of hard tubercles along a con- 

 siderable portion of their length. The whole surface of the 

 head and body is covered with small bony tubercles, most of 

 which are more or less stellated in form. Along several parts 

 of the body are rows of larger and more prominent tubercles, 

 with surfaces minutely granulated ; one row occupies the cen- 

 tral ridge of a portion of the back ; two or three tubercles are 

 placed on each side just in advance of the dorsal fin ; one 

 long row extends from the upper angle of the operculum in a 

 straight line to the upper part of the end of the fleshy por- 

 tion of the tail ; a second long row reaches from the space 

 above the pectoral fin to the lower part of the fleshy portion 

 of the tail ; another row of large size extends along the ab- 

 domen on each side as far as the commencement of the 

 anal fin. 



The mouth is wide ; the lips fleshy ; the lower jaw the 

 longest : a band of short and small teeth in each jaw : a 



VOL. II. 2 B 



