232 FISHES OF AUSTRALIA. 



carnivorous; their diet ranging from (occasionally) Man 

 himself, down to Crustaceans and Sea-Urchins. 



The great majority of these fishes are viviparous (that 

 is, the young are brought forth alive) ; the remainder being 

 oviparous (that is, the young are hatched out after the 

 deposition of the egg) . Only one of the very large Sharks 

 is known to be oviparous and that is the huge Greenland 

 Shark (Lemargus borealis), which is unique among Sharks, 

 in that it produces eggs without any horny covering; these 

 being deposited on the sea-bottom and left there to hatch. 

 The other oviparous Sharks are the small species known 

 as Dog-Fishes, the small Cat-Sharks and also those curious 

 and to Australians familiar "Bullhead" or Port Jackson 

 Sharks. The Rays that are oviparous, are those belonging 

 to the family Raiidce, popularly known as "Skates." 



Many of the Sharks and even a few of the Rays 

 more particularly the former are exceedingly formidable, 

 and are greatly feared in many parts of the world. 



Fossil remains of Elasmobranchs of many species, are 

 very abundant in some geological formations. These often 

 take the shape of fin-spines and dermal-plates. The former 

 are usually known as "ichthyodorulites." 



Elasmobranchs are considered to be of a very primi- 

 tive type among fishes, and amongst their number we must 

 look for the ancestors of the higher bony-fishes or 

 teleosteans. 



Many species of Sharks and Rays, of many families, 

 are known to inhabit the waters of our Australian coastline 

 and they include amongst their numbers, some of the most 

 ferocious "tigers of the deep." 



Amongst the Sharks may be mentioned: The Seven 

 gilled Shark (Notorhynchus indicus), the Port Jackson 

 Shark (Heterodontus philippi), the Crested Port Jackson 

 Shark (Heterodontus galeatus), the Wobbegongor Carpet 

 Shark (Orectolobus barbatus), the Tiger Shark (Galeo- 

 cerdo rayneri), the Blue Shark * (Prionace glauca), the 

 "Whaler," sometimes known as "River" Shark (Carchorias 

 brachyurus}, the Hammer - headed Shark (Sphyrna 

 zygana}, the Fox-Shark or Thresher ( Alopias vilifies), the 



* Not the Blue Pointer. 



