188 The True Sharks 
farther forward than in the Notidani. Each of the two dorsal 
fins has a strong spine. 
Family Heterodontide. — Among recent species this group 
contains only the family of Heterodontide, the bulihead 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 
Fic. 182. 
Fig. 1381,—Teeth of Cestraciont Sharks. (After Woodward.) d, Synechodus 
dubrisianus Mackie; e, Heterodontus canaliculatus Egerton; jf, Hybodus 
striatulus Agassiz. (After Woodward.) 
Fig. 1382.—Egg of Port Jackson Shark, Heterodontus philippr (Lacépéde). (After 
Parker & Haswell.) 
pointed anterior teeth, the fins are large, the coloration is strongly 
marked, and the large egg-cases are spirally twisted. All 
have five gill-openings. The living species of Heterodontide 
are found only in the Pacific, the Port Jackson shark of Australia, 
Heterodontus philippt, being longest known. Other species 
are Heterodontus franctsct, 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 
