10 



Fossil Fishes. 



with in strata of Cretaceous, Jurassic, and Carboniferous age. The 

 dentition (Figs. 21, 22) shows it to be admirably fitted for the 

 prehension and mastication of Crustacea and Mollusca. The teeth 

 are arranged in oblique rows upon the cartilaginous jaws, and vary 

 greatly in character between those forming the anterior series, 

 which consists of sharp, pointed teeth modified for seizing and 



Fig. 21.— Side-view of jaws of Port-Jackson Shark, Cestracion PMIip2)i (recent). 



Fig. 22. — Jaw of Fort-Jackson Shark, Cestracion Philippi (recent). 



holding their prey, and the lateral series, which are well adapted 

 by their flattened form for crushing shells. These lateral teeth 

 also vary greatly in the several rows (Fig. 22) covering the 

 two rami of each jaw, and they enable the palaeontologist clearly to 



