REVISION OF CARCHARHINID SHARK GENERA — SPRINGER 613 



dentition of mature males and females similar; sometimes cusps of 

 teeth of mature males slightly more erect than in females; enlarged 

 hyo mandibular pores 8-15 on each side of head. 



Denticles imbricate, 3-ridged in young and adults, 3-toothed in 

 young, 3-toothed or irregularly margined in adults. 



Color of preserved specimens variable: Body slate or purplish gray, 

 or gray brown above, pale below. Pectorals dark with a pale distal 

 edge, pel vies and anal pale or dusky; upper caudal lobe with a dark 

 margin on dorsal and ventral edges in young ; edging on ventral margin 

 absent in adults; lower caudal lobe without dark edging; first and 

 second dorsal fins dusky with posterior margin pale in adults, pale or 

 dark-margined in young. 



A low interdorsal ridge present in all specimens examined. Both 

 precaudal pits present, the upper better developed. 



Growth changes: There is a general tendency for distance from 

 snout tip to outer nostrils, eye, mouth, and pectoral origin to decrease 

 in percent of t.l. with increased t.l. Distance between inner corners 

 of nostrils and eye diameter also decrease in a similar manner. Dis- 

 tances from snout tip to pelvic, second dorsal, and anal origins tend 

 to increase in percent of t.l. with increased t.l., as do first dorsal 

 height, posterior margin of anal fin, anterior and distal margins of 

 pectoral fin, and length of lower caudal lobe. 



In large specimens there is a tendency for the axis of the upper 

 caudal lobe to become raised in relation to the horizontal axis of the 

 body. 



Too little information is available to establish the size at which 

 males fu'st mature, but based on the following tabulation it appears 

 that this size is greater than 583 mm.: 



The smallest non-embryo seen was 351 mm. and the largest embryo, 

 300 mm. Hubbs and McHugh (1950) reported free-living specimens 

 as small as 343 mm. and embryos as large as 327 mm. The largest speci- 

 men seen was 916 mm., but five embryos are indicated as having been 

 taken from a 1540 mm. female from Peru (Hildebrand, 1946). 



The five sibling embryos mentioned above have precaudal vertebral 

 counts of 79, 81, 82, 83, and 86, a range of 8 vertebrae. The known 

 range of variation for the species covers a span of only 19 vertebrae. 



I have noted no geographic variation in any character studied. 



