Fishes of Massachusetts. — . 533 
C. obscurus. Le Sueur. The dusky Shark. 
Journal Academy Nat. Sciences, vol. i. p. 223, et fig. 
In a paper by Le Sueur upon “Several new 
species of North American Fishes,” in the first vol- 
ume of the “ Journal of the Academy of Natural Sci- 
ences," a fish is described under the name of ** Sqau- 
lus obscurus," which I have little doubt he found 
in the waters of our state. Be that as it may, al- 
though he does not mention its locality, he fur- 
nishes us with a good figure of the species, and 
also of the upper and lower teeth. The only two 
species of shark with which this could be con- 
founded upon our coast, even by a careless obser- 
ver, are the “ Carcharias vulpes?—F'xz Shark, and 
“ Lamna punctata’ —Mackerel Shark ; in both 
these species, the edges of the teeth are smooth. 
In the * obscurus" however, they are deeply ser- 
rated. In the winter of 1837, my brother-in-law, 
Thomas M. Brewer, M. D., brought me a triangu- 
lar serrate tooth, he took from the jaw of a shark 
Which had been cast ashore at Nahant ; and in the 
summer of 1838, my friend Samuel Cabot, jr., sent 
me a dozen teeth which he procured from another 
shark at Nahant, evidently of the same species with 
the preceding. Inasmuch then, as these teeth are 
triangular and serrated, and the description of the 
Specimens seen by these gentlemen, answers to the 
plate of Le Sueur, I feel authorized in admitting this 
species here. The following is Le Sueur’s descrip- 
tion : 
