Fishes of the Western North Atlantic 415 



S-phyrna di-plana Springer, 1 94 1 



Hammerhead 



Figures 1 2 A, 81 



Study Material. Eight males and females, 470 to 639 mm. long, and the head of 

 another, about 1,200 mm. (calculated from size of head), from Rio de Janeiro and Rio 

 Grande do Sul, Brazil, and from the vicinity of Galveston, Texas, and male, about 

 1,340 mm., labelled "Europe" (Harv. Mus. Comp. Zool.). Male, 445 mm., and fe- 

 male, 504 mm., from Galveston, Texas; four specimens, two to three feet, from Colon, 

 and from Charleston, S. Carolina; head of one, about 1,375 mm. (calculated from breadth 

 of head), from Englewood, Florida; jaws of 1,850 mm. and 2,500 mm. specimens from 

 that same locality (U.S. Nat. Mus.). Also, photographs of head, region of caudal pe- 

 duncle, and second dorsal and anal fins, of a large Florida specimen (from Stewart 

 Springer). 



Figure 8i. Sfhyrna diflana, female, 639 mm. long, from Rio de Janeiro, Brazil (Harv. Mus. Comp. Zool., 

 No. 462). A Dermal denticles, about 55 x. S Left-hand upper and lower teeth, about 0.7 x natural size. 

 C Fourth upper tooth. D Twelfth upper tooth. E Third lower tooth. F Eleventh lower tooth. C-F, about 1.4 x. 

 G Head from below. 



Distinctive Characters. Diflana has long been confused with zygaena, but it is easily 

 distinguished from the latter by the facts that its head is scalloped in front at the midline 

 (rounded in zygaena), that its eyes are farther from its nostrils, and by the much shorter 

 interspace between the rear tip of its second dorsal and the origin of its caudal (cf. Fig. 



