FISHES OF MASSACHUSETTS. 187 



At the base of the fleshy portion of the Caudal fin, a deep 

 groove on each side, running half the length of this portion. 

 Caudal fin unequal in its lobes ; the upper, measuring along its 

 curve, twenty-three inches ; the lower, eighteen. Depth of 

 the caudal fin at its extremities, two and a half feet. 



Near the anus, imbedded in the flesh, I found a specimen of 

 the " Anthosoma SmithW — Leach. 



Large specimens of this shark, which is usually found only 

 three or four feet long, have been mistaken for the ^'Carcharias 

 glaucus" — Blue Shark — ^by our fishermen. Although the 

 Blue Shark may exist in our waters, still as I have not been 

 able to meet with it, nor with any one who has seen it, upon 

 whose scientific accuracy I can implicitly rely, I have erased 

 it from our catalogue, and substituted this species. The re- 

 marks made in my former report are applicable here, and are 

 therefore introduced. 



Spinax. Cuv. 



Generic characters. Two dorsal fins, ivith a strong spine at 

 the anterior edge of each ; no anal fin ; temporal orifices pres- 

 ent ; teeth in several rows, small and cutting. 



S. acanthias. Lin. The picked Dog-fish. 



Pennant's British Zoology, vol. iv. p. 88. 

 Shaw's Zoologj', vol. v. pt. ii. p. 33. 

 Mc Murtrie's Cuv. vol. ii. p. 288. 

 Yarrell's British Fishes, vol. ii. p. 400, et fig. 



This species is known in Great Britain by the name of 

 " Picked or Piked Dog,^' from the strong spine at the com- 

 mencement of each dorsal fin. Our fishermen called it " Dog- 

 fish.^^ In the spring and autumn, the dog-fish appear in 

 shoals in our bay ; they are frequently met with in immense 

 numbers. At their appearance, smacks are fitted out at Truro 

 and Provincetown for their capture, to the neglect of other 



