HISTORY OF THE FISHES OF MASSACHUSETTS. 403 



tlie abdomen. The tubercles of all these rows are granulated upon their sides, and 

 have a naked spine at their summit. The greatest depth of the fish is equal to 

 more than one half its length. The length of the head is less than one quarter the 

 length of the fish. The head is coyered with tubercles similar to those of the body ; 

 those on the posterior inferior angle of the operculum are larger than those on the 

 other parts of the head. The eyes are circular ; their diameter is equal to less than 

 one third the distance between the eyes. The nostrils are large, tubular. The teeth 

 are sharp and compact. A greater number of rows are in the upper than in the 

 lower jaw ; two small patches of minute teeth above and below in the pharynx. 

 Just back of the top of the head, a compressed ridge rises abruptly and curves upward 

 and backward to the posterior half of the body ; its depth in the middle being 

 equal to one third of its length ; and its length equal to one third the length of the 

 body of the fish. This ridge is formed of eight rays, which are perfectly distinct 

 when the fish is dissected, and readily distinguished also in the dried specimen. 

 The top of this ridge is covered with tubercles precisely similar to those which com- 

 pose the middle row on the body ; directly back of this dorsal ridge is a small flat 

 surface composing the space between it and the dorsal fin, whose sides are armed 

 with strong, prominent tubercles. 



The dorsal fin, which is rounded, and one sixth longer than high, with rays 

 niultifid, is situated directly behind the flat surface just referred to. 



The pectorals are longer at their base than the height of their highest rays ; the 

 height of the inferior rays is equal to about one fifth the height of the longest; 

 these fins are rounded when expanded. 



The ventrals, together with the anterior portion of the pectorals, form an oblong 

 disk, of a bright yellow color, with six well-marked lines on each side of its centre, 

 by which it is enabled to attach itself very powerfully to foreign substances. 



The anal fin, commencing about on a line opposite the beginning of the dorsal, 

 terminates on the same plane with that fin. 



The caudal fin, when not expanded, is a little higher than wide ; when expanded, 

 it is one quarter wider than high. The depth of this fin at its base to its extremi- 

 ties when expanded is as two to five. 



The fin rays are as follows:— D. 10. P. 20. A. 10. C. 12. 



Length, eight to twenty inches. 



Remarlcs. The whole appearance of this fish is very forbidding, being in young 

 specimens a soft, gelatinous, tremulous mass ; in older specimens it is of a much 

 firmer consistence; but in both it is covered entirely with firm, horny spines. 



