92 Peans. 



temperature and composition of the sea water, and 

 by the existence of a proper food supply. 



There is one peculiarity with regard to these 

 molluscs and, in fact, most inhabitants of the sea, 

 which is not generally known, namely, the frequency 

 of parasites, or as in many cases they are more 

 aptly termed " messmates," since they live in the 

 shell on apparently friendly terms with the oyster. 

 Mother-of-Pearl shells almost invariable hold one 

 or more, and on the Australian coast these inmates 

 are generally crabs, lobsters, worms and shrimp-like 

 creatures. One of the two former crustaceans is 

 almost always present, and it may be truly termed 

 a '' messmate ; " the latter are simply ordinary 

 parasites, and are not by any means universal. In 

 the shells found East of Cossack, on the West 

 Australian grounds, the oyster is usually accom- 

 panied by one soft-shelled brown crab, of | to \\ 

 inches in width : this is said to be poisonous. 

 Lower down the coast, the crab's place is taken by 

 two soft transparent-looking lobsters, faintly spotted 

 and tinged with red, the one three times as large 

 as the other : probably they are male and female. 

 These are delicious eating. The two principal claws 

 or pincers are very small in proportion to the body 

 of the lobster, especially in the larger of the two, 

 and the body reminds one more of that of a drone 



