/ 712 Bashford Dean Memorial Volume 



the ovaries of H. japonicus, the statement that the Port Jackson Shark spawns but 

 once a year cannot be accepted without further evidence. 



Waite (1896) writes that living eggs of Port Jackson Sharks (meaning both H. 

 phillipi and H. galeatus) are most abundant in spring (August and September) but are 

 found also throughout the summer. The empty egg cases may be found washed up on 

 beaches at any time of the year, especially after stormy weather. At Jervis Bay, New 

 South Wales, Haswell (1898) collected eggs of H. phillipi in blastula and gastrula stages 

 during September (a spring month in the southern hemisphere). It appears that he found 

 eggs in these stages in considerable numbers. He does not mention any later stages 

 collected during September. Whitley (1940) states that he has observed developing 

 embryos of H. phillipi in December, and young hatching in May. 



Regarding the eggs of H. francisci, Barnhart (1932) states that material collected 

 tends to show that several eggs are spawned during the year. 



In the region of Misaki, according to Dean's notes, spawning of Heterodontus 

 japonicus takes place throughout the entire year but the especial spawning season is 

 evidently the month of March. The divers brought in the maximum number of eggs 

 during April and May, and most of these were in stages which Dean estimated to be 

 a month or six weeks old. Throughout June, eggs in early stages of development were 

 brought in occasionally; throughout July, early stages were still more uncommon, perhaps 

 one in twenty; and later in the season, early embryos were found but rarely. Supple' 

 mentary evidence in regard to the breeding season was obtained by examining the ovaries. 

 Judging from the condition of the ovarian eggs. Dean concluded that H. japonicus spawns 

 a number of times during the "season", probably from six to twelve times, and that two 

 eggs are matured at about the same time. During the spring months the eggs are evidently 

 deposited at short intervals. This is deduced from the presence of almost ripe ovarian 

 eggs in Japanese Bullhead Sharks from which encapsuled eggs were obtained. Further 

 data bearing on the breeding season are given in the section on ''Rate of Embryonic 

 Development". 



EGG-LAYING HABITS; THE NESTS 



Waite (1896) wrote that the eggs of Cestracion (Heterodontus) phillipi were found in 

 moderately shallow water, wedged in among rocks. Whether they were actually dropped 

 into the crevices he did not know, but he thought it more probable that they were 

 deposited on the sand at the bases of the rocks, into the fissures of which they were after' 

 ward swept by the tide. They were so jammed, larger end outward, that they could 

 only be removed either by turning them around and withdrawing the small end first, or by 

 actually unscrewing them; both forces being most unlikely to occur under natural con- 

 ditions. When empty they are somewhat more pliable, which may account for the empty 

 capsules being loosened and cast ashore. In a later publication (1899) Waite wrote that 

 H. phillipi was common in Jervis Bay (New South Wales) which was for these fishes 

 a favorite breeding resort. Here, empty egg cases could be found in large numbers washed 



