24 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 119 



appearing extremely broad and shallowly U-shaped, with a shallow, 

 broad, median notch; small, pointed wings present on sides of rostral 

 node; anterior wing of olfactory cartUage prominent, pomted, and 

 projecting medially; anterior part of preorbital process long and 

 slender; posterior part of preorbital process terminating in an angular 

 knob. 



Teeth — ■ (one specimen examined); teeth not serrated; teeth 



in both jaws notably oblique, with none (except the median tooth) 

 perfectly erect, the teeth becoming progressively more oblique toward 

 corners of mouth, and those nearest the corners having cusps pointing 

 almost straight back; cusps visible on all teeth, although those near 

 corner of mouth in lower jaw poorly developed; teeth 6 through 10 in 

 upper jaw notably larger than others; tooth 1 notably smaller than 

 tooth 2 in lower jaw; teeth 2 through 10 in lower jaw gradually 

 increasing in size. 



mmM'^m 



Map 1. — Distribution of species. 



A Sphyrna blochii O Sphyrna mokarran 



(Solid = specimens examined; hollow = confirmed literature references.) 



Dermal denticles (examined from upper part of back beneath first 

 dorsal fin) not closely overlapping, the blades steeply raised ; length of 

 denticle (measured to tip of median marginal "tooth") as great, or 

 nearly as great, as uddth; five strong ridges usually present, and as 

 many bluntly pointed teeth usually present on posterior margin of 

 denticle, the outer ridges and teeth sometimes rudimentary or absent, 

 particularly in small individuals; median tooth on denticle ordinarily 

 slightly longer than more distal teeth; pedicel short and broad. 



Individuals gray or grayish brown dorsally, becoming more pale 

 below; no markings on fins. 



Maximum total length not recorded, possibly not more than several 

 feet. 



Range. — Sphyrna blochii is restricted to the Indo-West Pacific area 

 and is one of the two species of hammerheads not found in the Western 

 Hemisphere. It is known from the Persian Gulf (Blegvad and 

 L0ppenthin, 1944, p. 41, fig. 12) eastward throughout the East Indies, 



