NO. 3539 HAMMERHEAD SHARKS — GILBERT 25 



and north to southern China and the southern Philippines (Herre, 

 1930, p. 142). The species also has been recorded from Queensland, 

 Australia (Ogilby, 1908, p. 4) ; this area apparently represents both the 

 eastern and southern limits of its range. 



Sphyrna blochii, while perhaps not as closely restricted to continental 

 waters as Sphyrna tlhvro, nevertheless appears to be incapable of 

 traversing broad stretches of ocean, as evidenced by its absence from 

 outlying oceanic islands (map 1). 



Subgenus Sphyrna Rafinesque 



The subgenus Sphyrna, which includes S. zygaena, S. lewini, S. 

 couardi, and S. mokarran, is distinguished by only two unique char- 

 acters. These are: A large orbit, the greatest horizontal diameter 

 greater than distance from anterior margin of orbit to narial opening; 

 and a large maximiun size, individuals reaching a size of from 12 

 to 20 feet in total length. 



The subgenus is also distinguished by: A moderately expanded head, 

 the greatest width from 22.9 to 30.2 percent of total body length (in 

 specimens less than 1,000 mm. TL); first through fourth gill slits 

 nearly equal in length, and all somewhat longer than fifth gill slit; 

 anal fin and anal fin base relatively short, the former not over 11.0 

 percent, and the latter not over 7.5 percent, of TL; fifth gill slit situ- 

 ated distinctly behind, and fourth gill slit above (or very slightly 

 anterior to) insertion of pectoral fin; presence of a deep narial de- 

 pression; absence of an outer narial gi-oove; lobe of first dorsal fin 

 terminating w^ell anterior to insertion of pelvic fin; total number of 

 vertebrae ranging from 174 to 206 (usually 190 or more), with those 

 over posterior part of coelomic cavity not expanded in size. 



Sphyrna (Sphyrna) motcarran (Riippell) 



Figures 6, 7, 216, 226, Plates 2, 6a 



?Squalus tiburo (misidentification) Risso, 1810, p. 35. (Identification by descrip- 

 tion of head and reference to Lacepede, "Squale pantouflier" ; Nice; very rare.) 



Zygaena tudes Valenciennes, 1822, pp. 225-226. (In part; original description; 

 illustration of head; type specimens apparently represent more than one 

 species; types from Mediterranean Sea, Cayenne, and Coromandel; specific 

 name tudes subsequently restricted to a species other than one here called 

 Sphi/rna mokarran.) 



Sphyrnichthys zygaena (misidentification) Thienemann, 1828, p. 408. (General; 

 identification probable because teeth described as "gezalmelte.") 



Zygaena mokarran Riippell, 1835, pp. 66-67. (Original description ; figures of 

 head, teeth, and body; type specimen, a male 2510 mm. TL, Senckenberg 

 Museum no. 3590; type locality, Massaua, Red Sea.) 



Sphyrna malleus (misidentification) L. Agassiz, 1838, pp. 235, 303. (Identification 

 probable because teeth serrate.) 



Sphyrna mokarran Miiller and Henle, 1841, p. 54. (Red Sea.) 



