HETERODONTI 



amphistylic stock. In this connection it is interesting to notice 

 that the hyostylism of Heterodontus differs considerably from that 

 of other sharks (Huxley [230], Gegenbaur [153], and Fig. 58). 



Family CESTRACIONTIDAE. The dorsal fins are armed with strong 

 spines on the anterior edge, immediately in front of the endoskelefcil 



10 



