192 THE NATURALIST IN AUSTRALIA. 



A somewhat grotesque name has been bestowed on one member of the 

 Plectognathi by the Fremantle fishermen, with whom the Toad-fishes are familiarly 

 known as " Blow-fish." The species in question is one of the Trunk or Cow-fishes, 

 Oslracion lenticularis, differing from the type previously described, by the entire 

 absence of horn-like protuberances. In recognition of its obvious natural affinity 

 with the more familiar Tetrodons the title improvised for it is the "Bony Blow-fish." 



This list of Australian Phenomenal Fishes would be culpably incomplete without 

 a brief reference to the so-called Port Jackson Shark, Cestracion Phillipi, which has 

 been selected as the tail-piece illustration to this Chapter. The chief interest 

 attachable to this fish is centred in its remote antiquity. It representing the only genus 

 of a family group traceable back through the cretaceous and triassic to the more 

 remote Devonian or carboniferous formations. For a shark, the fish is of but small 

 size, rarely exceeding four or five feet in length. A tolerable idea of its form and 

 peculiarities may be obtained by a reference to the figure mentioned, which was 

 taken literally from life. As there shown, the head is especially large and massive, and 

 provided with conspicuous brow-ridges, while in front of each of the broad dorsal fins 

 there is a strong spine, as is found in the Piked Dog-fish, Acanthias, of the British seas. 



The armature of the mouth of Cestracion is highly characteristic. It consists 

 in front of prehensile elements, but to the rear of these there is a pavement-like 

 arrangement of crushing teeth, wherewith their owner breaks up and feeds upon 

 various descriptions of hard-shelled Invertebrata. Oysters are a favourite food of this 

 Shark, and, in consequence of its predilections for this bivalve, it has proved 

 a formidable enemy to oyster growers in both Tasmania and on the mainland 

 sea-board. At Spring Bay, in the former island Colony, the writer found it even 

 necessary to fence round certain of the Government Oyster Reserves with closely 

 wattled brush wood in order to protect the oyster stock laid down from this shark's 

 depredations. In some localities Cestracion feeds almost exclusively upon Sea-Urchins 

 or Echini, the sharp spines of which have apparently no other effect than the pleasant 

 titillation of its palate. The proof of the extent to which this piquant food is 

 favoured by this Shark is afforded by the fact that the entire pavement of teeth of 

 captured specimens are not unfrequently permanently stained a deep purple, through 

 constant indulgence in a dietary of the commoner purple Urchin. The name of Port 

 Jackson Shark was conferred upon Cestracion Phillifti with reference to its having 

 been first captured in that locality, to which it was then supposed to be restricted. 

 It has, however, been since found pretty well throughout temperate Australian waters, 



