The Emhryology of Heterodontus japonicus 713 



ashore or wedged in among rocks ; here also, in 20 fathoms of water and under, living eggs 

 might be freely obtained. 



Haswell (1898) likewise collected capsules containing living eggs of H. phillipi in 

 Jervis Bay, New South Wales. He states that he found many of these at low tide, 

 sticking in the crevices of the rocks, firmly wedged in by means of the spiral flange which 

 forms such a remarkable feature of the egg shell. 



So little is known about the spawning habits of H. galeatus that the following account 

 of their spawning grounds, quoted from Waite (1896), may be of interest: 



Although most rare upon the beaches, the eggs of C. [Heterodontus] galeatus prove to be 

 not uncommon when searched for in their native habitat. Through the kindness of Messrs 

 Darley and Grimshaw, I recently had the pleasure of searching for them 50 feet below the 

 surface. Although not successful in obtaining specimens, I got an excellent idea of the 

 general situation. In places, immense masses of brown seaweed grow to the height of two 

 or three feet so densely that scores of eggs may be securely concealed among them, protected 

 by their likeness to seaweed in color and texture. Mr. Cameron, the diver who kindly took 

 me in charge, told me that he always finds the eggs in the weed, so attached by their long 

 tendrils [Text-figure 37c] that it is scarcely possible to secure them whole, without cutting 

 the seaweed. In deep water they are freer from the violent disturbances, tending to detach 

 them, to which the eggs of the more common species (H. pihillipi) are subject 



Barnhart (1932) writes that eggs of H. francisci are frequently found wedged between 

 or under rocks in the extreme low-tide zone. 



In his notes Dean states that one can usually determine when a Heterodontid shark 

 is gravid by noting the greater abdominal girth. Also, a digital examination can readily 

 be made. In order to understand the process of egg laying in the Japanese Bullhead 

 Shark, one should be familiar with the external form of the egg capsule which is described 

 in a previous section of this article. 



Heterodontus japonicus deposits two eggs at about the same time. In numerous 

 instances encapsuled eggs were brought to the station (at Misaki) in pairs, and in the 

 same stage of development. It was therefore assumed that they had been deposited in 

 pairs. This assumption was verified on two occasions, when pairs of encapsuled eggs 

 were taken directly from the fish. Evidence that two eggs mature at about the same 

 time has been given in the section on the reproductive organs. 



Data as to the mode of depositing the egg are scanty. The fish is apt to fold its 

 pelvic fins around the cloacal region, and one must bend the fins aside in order to see if 

 a capsule is protruding. In one instance, a shark brought to the station deposited an egg 

 within a few hours (Text'figures 41a to 41d). When the fish was first examined (Text- 

 figure 41a) no trace of a capsule could be seen between the pelvic fins. An hour or two 

 later, the smaller end of the capsule protruded slightly (Text-figure 41b). Within an 

 hour, a second turn of the capsule's lateral frill or spiral lamina could be seen (Text-figure 

 41c) and in less than an hour later there appeared Text-figure 41d) the third turn of the 

 frill. At this time the egg slipped out, and Dean noted that in the final rapid phase of 



