. The Bashford Dean memorial volume :. Fishes; Sharks; Fishes, Fossil. The Embryology of Heterodontus japonicus 711 Maclay and Macleay (1879) state that Echini (Sea Urchins) form the chief food of Heterodontus galeatus and probably of all the genus. The strong dorsal spines and the prominent supraorbital ridges of these sharks enable them to force their way under rocks and stones in pursuit of their prey. A fine specimen of H. galeatus in the Macleay Museum had the dorsal spines worn down to half their proper length, evidently as a result of scraping against rocks, and its "viscera"
. The Bashford Dean memorial volume :. Fishes; Sharks; Fishes, Fossil. The Embryology of Heterodontus japonicus 711 Maclay and Macleay (1879) state that Echini (Sea Urchins) form the chief food of Heterodontus galeatus and probably of all the genus. The strong dorsal spines and the prominent supraorbital ridges of these sharks enable them to force their way under rocks and stones in pursuit of their prey. A fine specimen of H. galeatus in the Macleay Museum had the dorsal spines worn down to half their proper length, evidently as a result of scraping against rocks, and its "viscera" were full of finely triturated Echinus tests. My only information regarding the food and feeding habits of the Japanese Bullhead Shark is derived from Dean's manuscript, from which I quote the following: It [Heterodontus japonicus] is a bottom feeder, and is known to have a varied diet: crustaceans, mollusks, fish and sea urchins. With its formidable dentition it crushes mollusks of consid- erable size, and its well-worn grinding teeth show that the crushing of shells is a frequent habit. At first sight the mouth appears extremely small, and one gets the impression from the narrow ends of the jaws which are exposed that the fish is a "nibbler", and cannot open its mouth widely. The photograph, however (Text-figure 40) shows how completely the shark may open its mouth; and the captive fish is apt to offer many demonstrations of this habit. The jaws in such cases will sometimes be snapped together noisily, indicating great muscular leverage. In the case figured, the fish was an old one and its mouth was by no means in good order. On either side of the large teeth were tufts of sertularian hydroids; also there were half a do2;en leeches in the neighbor- hood, some specimens measuring about 2K inches in Text-figure 40. View of the wide-open mouth of a new-caught Hetero- dontus, presumably japonicus. Note the large grinding teeth in the posterior part of the roof
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