The True Sharks 



527 



farther forward than in the Notidani. Each of the two dorsal 

 fins has a strong spine. 



Family Heterodontidae. Among recent species this group 

 contains only the family of Heterodontidce, the bullhead sharks, 

 or Port Jackson sharks. In this family the head is high, with 

 usually projecting eyebrows, the lateral teeth are pad-like, 

 ridged or rounded, arranged in many rows, different from the 



FIG. 317. 



FIG. 318. 



FIG. 317. Teeth of Cestraciont Sharks. (After Woodward.) d, Synechodus 

 dubrisianus Mackie; e, Heterodontus canaliculatus Egerton; /, Hybodus 

 striatulus Agassiz. (After Woodward.) 



FIG. 318. Egg of Port Jackson Shark, Heterodontus philippi (Lacpede). (After 

 Parker & Haswell.) 



pointed anterior teeth, the fins are large, the coloration is strongly 

 m rked, and the large egg-cases are spirally twisted. All 

 have five gill-openings. The living species of Heterodontidae 

 are ound only in the Pacific, the Port Jackson shark of Australia, 

 Heterodontus philippi, being longest known. Other species 

 are Heterodontus francisci, common in California, Heterodontus 

 japonicus, in Japan, and Heterodontus zebra, in China. These 

 small and harmless sharks at once attract attention by their 

 peculiar forms. In the American species the jaws are less 



