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Memoir Sears Foundation for Marine Research 



laterally, as in Isurus, its breadth, including its lateral keel-like extensions, about 3 times 

 its depth, with a prominent transverse furrow above and below just in front of oria;in of 

 caudal. Dermal denticles minute, as in Isurus, 3-ridged, their free margins correspond- 

 ingly indented, the blades so nearly flat that the skin is hardly rough to the touch. 



Head 25 to 30% of total length. Snout shorter than in Isurus, its length in front of 

 mouth a little less than % of length of head, obtusely conical, but somewhat flattened 

 dorsally, with blunt tip; but in large, heavy specimens, suspended or dragged up on the 

 beach by the front of the mouth, the head is often greatly distorted in appearance as seen 

 in photographs, since the upper jaw is slightly protrusible. Eye small, circular, its anterior 

 margin a little posterior to front of mouth. Spiracle lacking in fresh specimens seen by us, 

 pore-like if present, behind eye by a distance about equal to length of snout in front of 

 mouth. Gill openings as in Isurus, noticeably long, the 5th a little the longest, between 

 1.5 to 2 times as long as snout in front of mouth, the ist shortest, the spaces between them 

 successively narrower from front to rear, that between 4th and 5th being only about Yz as 

 great as that between ist and 2nd, the 5th close in front of origin of pectoral and curving 

 posteriorly around latter. Nostril narrow, transverse, near side of head, nearer to mouth 

 than to tip of snout, its anterior margin with very low subtriangular lobe. Mouth broadly 

 rounded, a little more than twice as broad as high. Labial furrows very short, the lower 

 concealed except when mouth is open. 



^^^p^f9?^^ 



Figure 22. Carcharodon carcharias, about six feet long, from Long Island, New York (Amer. Mus. Nat. Hist., 

 No. 14773). ^ Upper and lower teeth, right-hand side, about natural size. B Fourth upper tooth. C Seventh 

 upper tooth. D Third lower tooth. E Seventh lower tooth. B-D, about 2 x. 



