THE SHORE FISHES OF PERU 27 



Genus SPHYRNA Rafinesque, 1810 



The characters of the genus are sufficiently indicated in the inniily 

 description. 



KEY TO THE SPECIES 3 



a. Second dorsal with a long posterior lobe, about twice as high as anterior lobe; 

 anterior margin of head with 3 lobes; a straight line connecting centers 



of eyes passing over the mouth zygaena (p. 27) 



aa. Second dorsal with a short posterior lobe, about same height as anterior one; 

 a straight line connecting center of eyes passing in front of mouth. 

 h. Anterior margin of head lobed, not forming a continuous curve. 



c. Head broad, definitely hammer-shaped, its anterior margin more or loss 



irregularly 4-lobed; teeth heavy, serrate tudes 



cc. Head narrower, not definitely hammer-shaped, but more or less kidne^^- 

 shaped, its anterior margin irregularly oval; teeth slender, not serraf-c. 



corona 

 hh. Anterior margin of head not lobed, forming a continuous curve. 



d. Anterior margin of head with a slight median angle; teeth with low cusps, 



which become progressively smaller toward angle of jaw, entirely absent 

 on 1 or 2 rows in upper jaw, and on 4 or 5 rows in lower jaw; preoral 



length 1.5 to 1.75 in space between nostrils vespertina 



dd. Anterior margin of head forming a broad continuous curve, without iufii- 

 cation of a median angle; teeth all with cusps; preoral length 2.2 in 

 space between nostrils media 



SPHYRNA ZYGAENA (Linnaeus) 



Peje-martillo; Ckuz; Medialuna; Cornuda; Peje-capblo 



Squalus zygaena Linnaeus, 1758, p. 234, Europe, America (original description). 

 Zygaena peruana Philippi, 1887, p. 545, pi. 2, fig. 2, Peru (original description). 

 Sphyrna peruana Abbott, 1899, p. 328 (reference to Philippi). 

 Sphyrna zygaena Starks, 1906, p. 763, Callao, Peru. — Evermann and Radcliffe, 



1917, p. 5, Lobos de Tierra, Peru (references; measurements of a 100-cm. 



specimen).- — Nichols and Murphy, 1922, p. 504, Lobos de Tierra, Peru. — • 



Fowler, 1941a, p. 224 (references). — Beebe and Tee-Van, 1941, p. 114 



(range; field characters; size; references). 



Only the head of an individual, 154 cm. long, taken with a line 

 trawl in about 18 fathoms near Cabo Blanco is at hand. 



The species is recognized within its genus by the 3-lobed anterior 

 margin of the head; the rather forward position of the eye, the 

 diameter of which is greater than the lateral extension in front of it; 

 a straight line connecting the middle of the eyes passes over the 

 mouth; the lateral teeth have broad shoulders posteriorly, sometimes 

 set off by a notch, and the margins of the teeth as well as the expanded 

 shoulders are minutely serrate (becoming entire with age) ; and the 

 produced posterior lobe of the second dorsal is about twice as high 

 as the rest of the fin. 



' Although only one species, zygaena, has been definitely reported from Peru, a key, somewhat modified 

 after Beebe and Tee-Van (1941, p. 114), to all the species known from the American side of the tropical 

 Pacific is included as an aid in recognizing additional species, if taken in Peru. 



