SHARKS. 



35 



seas ; the average size is twelve or fifteen feet, but some species 

 attain to a length of twenty-five feet. 



The common Blue Shark, so dangerous to persons bathing in 

 •the tropics, is Carcharias glaucus. The genus is represented in 

 the exhibited series by the White Shark, Carcharias lamia, 57 ; 

 the Black-finned Shark, Carcharias melanopterus, 58 ; Carcharias 

 menisorrah, 60 ; the jaws of Carcharias acutidens, 61, and 

 Carcharias dussumieri, 59 ; and a specimen of Carcharias 

 hemiodon, 1125, suspended from the rail opposite Wall-case 18. 

 In some parts of India and China Shark's fins are used for making 

 soup, the fins being mostly those of Carchariid Sharks. They are 

 sold in the form in which they are exhibited (specimen 70). The 

 trade in Shark's fins is less now than formerly; in the year 1845 

 over four hundred tons of them were exported from Bombay to 

 China. 



In the genus Galeocerdo the spiracle is minute ; there are 

 pits at the root of the caudal fin, one above and one below. 

 In the terminal lobe of the caudal fin there is a notch, situated 



Fig. 20. 



■Galeocerdo arcticus, a Shark of* wide distribution. 

 Also a single tooth of the same Shark. 



at the point where the vertebral column ends, which is not 

 present in the other genera of the family. The teeth are subequal 

 in the upper and lower jaws ; they are oblique, serrated on both 

 margins, and have a deep notch on the outer or posterior margin 

 (see teeth 63 and fig. 20). A small specimen of the Tiger Shark, 

 Galeocerdo tigrinus, 62, is shown ; hanging from the rail opposite 



d2 



Galeo- 

 cerdo. 



