THE LOWER FISHES 



137 



Fig. 48. Top. One of the authors is holding a small nurse shark, Ginglymostoma. 

 The barbels, used for locating prey by taste and touch, are clearly shown. In spite of 

 the docile nature of this shark, it has occasionally been known to bite. Bottom. 

 The inside of the jaws of the tiger shark, Galeocerdo, are lined with several rows of 

 teeth. Those at the bottom of the picture replace those at the top as the latter are 

 worn down. 



