FISHES OF MASSACHUSETTS. 9 



below ; denticulations much smaller upon the upper portion of 

 posterior edge. The lowest edge of operculum very slightly- 

 serrated ; a spine at its posterior angle, and above this an 

 obtuse point. The lateral line commences at the upper pos- 

 terior portion of the operculum; and inclining a little upward, 

 is lost on the membrane connecting the middle rays of the 

 caudal fin. 



The first Dorsal fin commences about six lines back of the 

 base of the pectorals, and is about half as high as long. 



The second Dorsal fin is rather more than two thirds the 

 length of the first dorsal : its first ray is spinous. 



The Pectorals commence on a line with the posterior angle 

 of the operculum : length equal to one third their height. 



The Ventrals arise back of the pectorals, and are two lines 

 shorter than those fins. 



The Anal fin commences on a line with the fifth ray of the 

 second dorsal : the height and length of this fin are equal. 



The Anal and Dorsal fins terminate on the same plane. 



The fin rays are as follows : D. 9. 1-12 ; P. 15 : V. 1-5 ; 

 A. 3-9 ; C. 17. 



Centropristis. Cuv. 



Generic characters. A single dorsal fin : hranchiostegous 

 rays 7 : all the teeth smull and crowded : 710 canini : preoper- 

 culum dentated, and operculum spinous. 



C. nigricans. Cuv. The Black Perch. 



Trans. Lit. et Philosoph. Soc. N. Y. p. 415, et fig. 



Mc Murtrie's Cuv. v. ii. p. 107. 



Cuv. et Valeiic. Hist. Nat. des Poiss. t. iii. p. 14. 



I have never heard of this species, the Perca varia of 

 Mitchell, having been taken north of Cape Cod. The only 

 specimen met with. Dr. Yale kindly sent me from Holmes 

 Hole, where it is called Mack fish and Mack basse: he informs 

 me that it has been taken there in great numbers in May, 

 2 



