SELACHOIDEI. 



321 



Fig. 114.- 



mandible measuring 22 inclies.^ The whole length of the 

 fish was 3GJ feet. 



Carcharodon teeth are of very common occurrence in 

 various tertiary strata, and 

 have been referred to several 

 species, affording ample evi- 

 dence that this type was much 

 more numerously represented 

 in that geological epoch than 

 in the recent fauna. Some 

 individuals attained to an 

 immense size, as we may 

 judge from teeth found in 

 the Crag, which are 4 inches 

 wide at the base, and 5 inches 

 long, measured along their 

 lateral margin. The natural- 

 ists of the " Challenger" expe- 

 dition have made the highly interesting discovery that teeth 

 of similar size are of common occurrence in the ooze of the 

 Pacific, between Polynesia and the west coast of America. 

 As we have no record of living individuals of that bulk hav- 

 ing been observed, the gigantic species to which these teeth 

 belonged must have become extinct within a comparatively 

 recent period. Nothing is known of the anatomy, habits, 

 and reproduction of the • surviving species, and no oppor- 

 tunity should be lost of obtaining information on this Shark. 



Odontaspis. — The second dorsal and anal are not much smaller 

 than the first dorsal. No pit at the root of the caudal. Side of 

 the tail without keel. Mouth wide. Teeth large, awl-shaped, 

 with one or two small cusps at the base. Gill-openings of mode- 

 rate width. 



Large Sharks from tropical and temperate seas; t^^o species. 



1 The cartilaginous jaws of Sharks shrink at least a third in drying, and, 

 therefore, cannot be kept at full stretch without tearing. 



Y 



-Tooth of Carcharodon 

 rondeletii. 



