256 



BULLETIN OF THE BUREAU OF FISHERIES. 



The teeth of this species resemble those of H. brevirostris more closely than the other speciesof Car- 

 charhinus, the difference being so slight as to suggest the advisability of including the species of that 

 genus under the genus Carcharhinus. 



Denticles. — The sculpturing of the dermal denticles varies with age. In specimens 60 to 70 cm. in 

 length the denticles are small (0.25 mm. long by 0.28 mm. broad in a 70 cm. specimen), three-keeled, 



subequal, close-set, 

 imbricated; keels low, 

 distinct ; apical margin 

 three-lobed, with deep 

 incisions between the 

 lobes; basal margin 

 rounded; pedicel short 

 and stout ; basal plate 

 large, rhomboidal. 



In two examples 

 135 and 175 cm. in 

 length, the denticles 

 are five to seven keel- 

 ed; apical margins rel- 

 atively smooth, the 

 apical lobes in most 

 casesbeing worn down. 

 In places where the 

 skin has been abraded 

 and new denticles are 

 being formed, the 

 changes in form may 

 be noted. In the early 

 stages of development, 

 the denticles are usu- 

 ally smooth, ovate in outline; later a sharp median keel appears, followed by a lateral one on each 

 side; at this stage the apical margin may be entire or deeply three-lobed as in individuals 60 to 70 cm. 

 long. Later one or two additional lateral keels on each side appear. 



Measurements op a Female, 70 Cm. (27K Inches) Long, Taken in the Pound Net Aug. 27, 1913. 



Fig. 



-Denticles, Carcharhinus limbatus, 70 cm. long, from Beaufort, N. C. 



Total length 700 



Depth at origin of first dorsal 10. 8 



Tip of snout to— 



Origin of first dorsal 22.4 



Anterior margin of eye 4. 8 



Upper angle of first gill slit 14. o 



Upper angle of fifth gill slit 17-9 



Base of pectoral 17- 1 



Front of mouth 5-7 



Center of nostrils 3-7 



Horizontal diameter of eye i-3S 



Distance between nostrils 3-7 



Distance *^etween angles of mouth 6. 3 



Height of— 



First gill slit 2.5 



Second gill slit 2.7 



Third gill slit 2.9 



Fourth gill slit 28 



Fifth gill slit 2-3 



Length of anterior margin of first dorsal 9-6 



Height of first dorsal 6. S 



Length of posterior margin of first dorsal 3.1 



Base of first dorsal 7- S 



Distance between dorsals I3' 7 



Length of anterior margin of second dorsal 3.4 



I^ength of posterior margin of second dorsal 2-9 



Base of second dorsal 3-2 



Length of anterior margin of pectoral 12. 2 



Length of posterior margin of pectoral 3.4 



Length of distal margin of pectoral 8. s 



Distance from origin of pectorals to base of ventrals 18. 6 



Length of anterior margin of ventrals 4. 2 



Length of posterior margin of ventrals 3.8 



Base of ventrals 2.6 



Distance between ventrals and anal 6.6 



Length of anterior margin of anal 4.0 



Length of posterior margin of anal 2-6 



Base of anal. 3'3 



Distance from base of anal to origin of caudal 4.0 



Length of upper caudal lobe 19-6 



Length of ower caudal lobe 8.4 



