The Embryology of Heterodontus japonicus 693 



falciform; the height is exactly twice the length of the portion of the base attached to the 

 back. The spine is small and acute (as compared with that of H. pMlipi), being only half 

 the length of the fin. The second dorsal is shaped like the first, but is less in height, and 

 its base of attachment to the back is about the same. The distance between the two 

 dorsals is equal to that between the second dorsal and the commencement of the caudal 

 fin, and to that between the first dorsal and the eye. The pectorals are large and tri- 

 angular, and about equal in length to the caudal. The ventrals (pelvics) are situated in 

 a line intermediate between the two dorsals. The anal commences distinctly behind the 

 second dorsal, and does not nearly reach the caudal. The lower lobe of the caudal is very 

 deeply and less than rectangularly notched. The authors do not mention the hump on the 

 anterior part of the body, which is quite prominent in their figure representing a lateral 

 view (my Text'figure 23). 



To Bashford Dean we are indebted for the only photograph of a fresh-caught adult 

 Japanese Bullhead Shark on record. This was published (Dean, 1904) in the Popular 

 Science Monthly in an article entitled "A Visit to the Japanese Zoological Station at 

 Misaki" and is reproduced herein as Text-figure 3, page 655. The original legend reads 

 "A Freshly Caught Port Jackson Shark", but since Dean states in the accompanying text 

 that a Port Jackson Shark is abundant at Misaki, it is evident that he was using the name 

 in a generic, not a specific sense — for Heterodontus phillipi does not occur at Misaki. 

 Thus the species is almost certainly H. japonicus, though H. zebra, a more slender form, 

 does occur somewhat rarely in the vicinity of Misaki. The photograph does not show the 

 color pattern, which would make identification easy. In Dean's photograph, one must 

 make some allowance for the trick of the camera in enlarging objects in the foreground : 

 the pectoral fin is probably a little too large. Since the mouth is partly open, the lower 

 jaw has sagged and the cranium is slightly upraised. 



Among Dean's records there is a faded photograph showing a dorsal view of an 

 adult or nearly adult Heterodontus, presumably japonicus. The supraorbital ridges are 

 well shown. They are strongly upraised, though narrow, and approach each other at 

 their anterior ends, diverging posteriorly. At their posterior ends they terminate 

 rather abruptly, though not so abruptly as in H. galeatus (Text-figure 20 and in Maclay 

 and Macleay's lateral view). The breadth of the head, measured between the first pair of 

 gill-covers, equals 19 per cent of the total length. The pectoral fins are extended, and the 

 distance from tip to tip equals 56 per cent of the total length. 



A young female specimen of Heterodontus japonicus in the collections of the American 

 Museum of Natural History measures about 280 mm. (eleven inches) in length "over all". 

 It is described on page 757 and portrayed in Text-figure 65, of the present article. 



There remains to be considered a figure of the Japanese Bullhead Shark contained in 

 a folio volume entitled "Illustrations of Japanese Aquatic Plants and Animals", published 

 by the Japanese Fisheries Society in 1931. An adult specimen of Heterodontus japonicus 

 is there portrayed in color. Upon comparing this figure with those of other authors 

 (including the photograph by Bashford Dean reproduced in my Text-figure 3) one gets 



