FISHES OF THE GULF OF MAINE 



45 



to Ecuador on the Pacific Coast of America, or 

 represented there by a very close relative. 9 



Occurrence in the Gulf oj Maine. — Our only 

 reason for including the shovel-head here is that 

 a stray specimen has been reported from Massa- 

 chusetts Bay. 10 It has also been taken once at 

 Newport, R. I., and a commercial shark fishery 

 that was carried on in Nantucket Sound in the 

 summer of 1918 is said to have yielded six of them. 11 



Common hammerhead Sphyrna zygaena 

 (Linnaeus) 1758 

 Bigelow and Schroeder, 1948, p. 436. 



' On this point, see Bigelow and Schroeder, Fishes of the Western North 

 Atlantic, Pt. 1, 1948, p. 425, footnote 20. A shark has also been reported as 

 tiburo from China and from the Philippines, but without convincing evidence 

 as to its identity. 



10 By Oarman, Mem. Mus. Comp. Zool., vol. 36, 1913, p. 161. Apparently 

 the specimen is no longer in existence. 



11 Personal communication by R. n. Bodrnan, who operated this fishery. 



Description. — The very differently shaped head 

 of the hammerhead, the shape of its anal fin with 

 much more deeply concave posterior margin, and 

 the fact that the outermost four or five of its lower 

 teeth on each side are blade-like, like those nearer 

 the center of its mouth, are ready field marks to 

 separate the hammerhead from the shovelhead 

 (cf. fig. 16 with fig. 15). The anal fin, too, is only 

 about as large as the second dorsal in the hammer- 

 head (considerably larger than the second dorsal 

 in the shovelhead). Otherwise the positions and 

 shapes of the fins and the size and shape of the 

 tail are much alike in the two species. 



Color. — Leaden or brownish gray above, shading 

 along the sides to pure or grayish white below; the 

 tips and edges of the dorsal and caudal fins are 

 more or less dusky; and the tips of the pectorals 

 are black on some specimens. 



Figure 16. — Hammerhead (Sphyrna zygaena), female, about 27 inches long, from Nahant, Massachusetts. A, head 

 from below, about one-third natural size; B, second upper tooth; C, ninth upper tooth; D, third lower tooth; 

 E, ninth lower tooth; about 4 times natural size. From Bigelow and Schroeder. Drawings by E. N. Fischer. 



