Zoology.-] NATURAL HISTORY OF VICTORIA. [Fishes. 



Plate 118. 



HETERODONTUS PHILLIPI (Lacep. sp.). 



Port Jackson Shark, or Bull-dog Shark. 



[Genus HETERODONTUS (Blainv.) = CESTRACION (Ccv., not Klein.) (Sub-king- 

 dom Vertebrata. Class Pisces. Order Cbondropterygii. Sub-order Plagiostornata. Tribe 

 Selacboidei. Eamily Heterodontidaj.) 



Gen. Char. — Ovate, fusiform ; head large, blunt, rounded in front, high, cuboid, with a 

 prominent longitudinal ridge over each eye ; mouth narrow, nearly terminal ; upper lip divided 

 into 7 lobes (1 median and 3 on each side) ; lower lip with one long fold on each side ; nostrils 

 confluent with mouth cavity; spiracles very small, below and behind the eye. Gill-openings 

 small. Teeth alike in both jaws, the median front rows very small, acutely tricuspid when 

 young, simple and with obtusely triangular cusp in middle age, blunt and hexagonal when old ; 

 more posterior teeth large, oblong, longer than broad, flattened, arranged in oblique, spiral rows 

 on each side of jaw, the anterior and posterior ones smaller than those in middle. Fins ; Two 

 dorsals, each with a small, smooth spine on front edge, anterior dorsal between pectorals and 

 ventrals, posterior dorsal in front of anal. Shagreen spines, or granules, of skin irregularly 

 stellate on upper surface. East and West Pacific and Indian Oceans.] 



Description. — Form semifusiform, tapering- rapidly from the head to the tail. 

 Head large, about as high as broad, bluntly rounded in front, muzzle short ; two 

 prominent, bluntly rounded ridges arise, one on each side, beginning about over the 

 first gill-slit, arching over the eye and descending with the slope of the profile (which 

 is nearly straight at an angle of about 40° from longitudinal midline) to about over 

 angle of mouth, bounding a deep concavity along top of head ; their distance apart 

 about equal to distance from anterior edge of orbit to upper end of first gill-opening ; 

 height of head at orbit about one-seventh of total length, including caudal fin ; 

 length of head from tip of snout to first gill-opening about one-sixth the length of 

 body ; mouth and nostrils nearly terminal on under-side ; upper lip as wide as head, 

 divided into three lateral lobes, the outer one large, longitudinally oblong, flat, 

 overlapping under lip, next a nearly circular spirally involute lobe going nearly 

 round the large nostril, and next a broad rounded lobe ; the middle occupied by a 

 thin semicircular edge exposing the anterior median rows of teeth, which are promi- 

 nent ; lower lip with a long fold on each side from angle to the middle, exposing the 

 median rows of teeth in front. Spiracle minute, about the vertical diameter of the 

 orbit below hind margin of eye. Orbit twice as long as wide, close under the ridges 

 on the upper margin of the sides of the head; pupil longitudinally horizontal, 

 elliptical. Teeth : Upper and lower jaws alike, but a few more rows in upper than 

 lower jaw; quadrate, oblong in front, the rami widening so as nearly to touch about 

 the middle of their length, leaving an ovate median space, be} r ond which they narrow 

 and divaricate to the back; teeth in about 27 rows, about 12 rows of about 13 teeth 

 each, longitudinal, and slightly diverging in front, each tooth of which is very small, 

 triangular, transversely ovate, front ones blunt, forming acutely angular simple erect 

 cusps farther back, and most acute, and with 1 or 2 lateral cusps in young teeth 

 behind ; 7 or 8 rows spirally arranged obliquely on each ramus from within, for- 

 wards and outwards, of large, flattened, slightly convex teeth, obliquely rhomboidal, 

 each with a narrow longitudinal ridge nearer the outer margin, and having the surface 

 sculptured with transverse vermicular ridges and small pits ; teeth of the fifth row 

 from the back largest, all longer than wide. Fins : Pectorals very large, about one- 

 fifth the length of the fish, width about two-thirds the length ; posterior edge nearly 



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