THE AUSTRALIAN MUSEU.M MAGAZINE. 



109 



soe the crab standing- up on the tips passes ail tliu rest of its life in this 

 of all its legs and looking like some upside-down condition, 

 self-satisfied old person, as it deliberate- W'lien the tide rises, a central door in 



ly raises each "hand" alternately to its the shell of the barnacle opens, and the 

 mouth. Talking- of feeding reminds me animal searches for food by thrusting 

 that the stomach of the crab is remark- plume-like feet in and out witli a sweep- 

 able in having a set of working teeth ing motion, which draws to them the 

 inside it. The lining of the organ is minute life on which the creature feeds, 

 thickened and har- 

 dened with lime, so 

 as to make a sort 

 of framework, and 

 on this there are 

 three hard caleai-e- 

 ous teeth which work 

 into eac;h other ana 

 jjroject into the 

 stomach cavity. Very 

 ])owerful muscles 

 work these teeth and 

 cause them to grind 

 up the food. It is 

 to be hoped that the 

 <:i-ab does not siatfer 

 too often frori. 

 toothache ! 



A young crab is 

 very unlike a crab. 

 When it first comes 

 out of the egg it 

 is a free swimming 

 little creature with 

 a thin, loose, trans- 

 parent skin all about 

 it. As it gTows it 

 casts its skin from 



time to time, develops legs, loses its long 

 tail and gradually becomes the adult 

 crab which often cannot swim at all. 



BARXACLES. 



Acorn barnacles are found all round 

 the rocks, more often exposed to the 

 air than not. They have made fair 

 progress towards becoming land crea- 

 tures, but are prevented from fuither 

 progression by their fixed habit. Yet to resist Ijattering or crushing, for most- 



Rock Crab (Leptograpsus variegatus). The commonest crab on the 

 coast of New South Wales. To be seen everywhere along the rocky 

 foreshores, swiftly retreating into a safe hiding as an onlooker 



approaches. 



Photo. — A. MnsKrave. 



Along a stretch of barnacle-covered 

 shore (juite a distinct swishing, grinding' 

 sound may be heard as the acorn shells 

 get 1)usy in the rising tide. 



SHELLS. 



The whelks of our beaches (which 

 are not tlie sam*^ as the European 

 whelks) all have very strong shells, 

 usuallv with some notable device on them 



when young, the larva is a (|uite active 

 creature. But after a while the young 

 barnacle attaches itself to a rock, grows 

 a hard armour casing around itself ami 

 loses all powers of locomotion. It is 

 fixed to the rock head downwards and 



ly they are fond of the rocky shores 

 where the waves have full play. The 

 small rock-whelk, for example, dark 

 bj-own in colour and about an inch long, 

 has a shell studded with girdles of small 

 hard knobs, while the "belted whelk" 



