28 



PROCEEDINGS OF THE NATIONAL MUSEUM 



precaudal pit; a shallow upper precaudal pit, with an acutely pointed 

 posterior ridge to upper precaudal pit (fig. 216); an anterior-median 

 pore patch in which the outer-posterior corners are sharply angled 

 and the posterior edge is straight (fig. 226); presence of a rostral 

 fenestra, and several other chondrocranial characters (pi. 6a). 



A comparison of S. mokarran wdth other members of the genus is 

 presented in table 1. 



Description. — Meristic data appear in table 3. Characters men- 

 tioned in the diagnoses of the subgenus Sphyrna and S. mokarran are 

 not repeated here. 



Figure 7. — Sphyrna mokarran: a, head of small adult, 1,660 mm. TL, from Englewood, Fla., 

 0.09 X natural size (USNM 108453); b, teeth series from left side of upper and lower 

 jaws (USNM 108453), about natural size; c, fifth upper tooth; d, twelfth upper tooth; 

 e, fifth lower tooth;/, eleventh lower tooth, (c-f, about 1.5 X.) (From Bigelow and 

 Schroeder, 1948, p. 429.) 



Head moderately expanded, the greatest width from 22.9 to 27.3 

 percent of TL (in specimens less than 1,000 mm. long); shallow scal- 

 lops present on anterior margin of head about halfway between nares 

 and tip of snout; outer posterior corner of lateral expansion of head 

 posterior to corner of mouth in smaller specimens, anterior to corner of 

 mouth in larger individuals; narial flap broad, broadly pointed at tip, 

 with the outer edge ciu"ving abruptly inward; orbit large, the hori- 

 zontal diameter almost equal to length of shortest (fifth) gill slit; 



