NOTES ON THE KELP SHELL, CANTHARIDUS IRISODONTES. 

 By ERNEST MAWLE 

 i Communicated by Charles Hedley, F.L.S.) 



HrtW5*£&» 4 flk 



A Shell Necklace. 



As mementoes of their visit to Tasmania tourists often purchase at Hobart necklaces of sea shells — 

 dainty, glittering trinkets of rainbow colours. The beauty of these shells attracted the admiration 

 of even the aboriginals, ami a portrait oi a native girl, wearing a necklace of them, has been left bj 

 Peron. The savages are said to have brightened their shells by burying them with seaweed. Probably 

 an acid produced by the decaying plants dissolved away the exterior of the shell and exposed the 

 brilliant under surface. 



These shells have been popularly called " Kelp Shells," because thev inhabit the fronds of sea 

 weed. There are two kinds, a larger shell, Cantharidus eximius, which was used by jewellers as a 

 knob for ladies' hat pins, and a smaller one, C. irisodontes, the necklace shell, properly so called. 

 C. eximius prefers the giant kelp, Macrocystis, but C. irisodontes usually avoids that plant and chooses 

 rather to dwell on the various smaller algae, such as Sargasso and Eklonia. It ranges from low water 

 down to five fathoms, but is most plentiful at a depth of eight or ten feet. But a large variety of 

 C. irisodontes has taken to living on the giant kelp. It is distinguished from C. eximius, whose home 

 it shares, by being only half as large and by being smooth instead of spirally grooved. 



Cantharidus eximius. 



Cantharidus irisodontes. 



The shells of C. irisodontes are gathered for the market about March, when they are in the best 

 condition. A pole, ten to fourteen feet long, armed with a knife, or with two prongs arranged like a 

 Canterbury hoe, is used to tear up the weed. The bunches thus pulled up are lifted into the boat 

 and sharply shaken over a sheet spread across the bows. The shells drop off the weed onto the sheet, 

 and are afterwards thrown into a basin of fresh water to kill and wash them. 



An active collector can obtain nine quarts of shells a day. The price paid for them varies from 

 2s. 6d. to 4s. a quart, according to their size and lustre. Parrot fish search the sea weed and eat 

 immense quantities of C. irisodontes. In January and February, when they are most abundant, the 

 stomach of every parrot fish is full of their broken shells. 



