FISHES OF MASSACHUSETTS. 197 



eyes, passing towards the snout, and almost back of the eyes. 

 Two dorsal fins ; the first, commencing back of the middle of 

 the body, three inches long, nine inches high. Between 

 this and the second dorsal, one inch. Second dorsal, six inches 

 long ; more than an inch high, in its highest part. Anal fin, a 

 mere fringe. Caudal fin, appears like the extremity of the 

 solid portion of the body, very much compressed. 



P. nigricans. Le Sueur. The bluish Lamprey. 

 Trans, of Amer. Phil. Soc. new series, vol. i. p. 385. 



This species is generally found attached to other species of 

 fishes ; it is frequently affixed to mackerel; less often to cod ; 

 and the three specimens I have met with, were taken adhering 

 to haddock. From the largest of these, seven inches in length, 

 the following description is made : Upper part of the body, 

 of a deep blue color; beneath, bluish white. Anterior third of 

 the body, cylindrical ; back of this, compressed ; very much 

 so towards the tail. Head oval, flattened on the top ; length 

 of the head, from the snout to the posterior angle of the eye, 

 to the length of the fish, less than one seventh. Seven bran- 

 chial orifices, running obliquely backwards and downwards 

 from the eyes. Mouth, circular ; half an inch in diameter ; 

 surrounded by a fleshy margin ; armed within, with numerous 

 incurved teeth, or horny spines, projecting from widened bases, 

 resembling the spines with which the Raiae are armed. 

 There are three teeth in the throat ; two higher up than the 

 third, which is in front of and between the others. In the 

 general appearance of the teeth, there is great resemblance be- 

 tween those of this species and the preceding. Eyes moderate 

 in size ; pupils black ; irides silvery. Between the eyes, on 

 the top of the head, a small white spot ; in front of this spot, a 

 spiracle. 



The first Dorsal fin commences back of the middle of the 

 fish ; its posterior portion is rounded ; its height to its length, 



