A NEW SOUTH 
AUSTRALIAN 
SHELL 
by W. G. BUICK, A.U.A. 
and W. M. BOWDEN 
Of all the various South Australian shells one 
group has received more attention in concho- 
logical literature than any other. The two 
species in this genus are uncommon enough to 
have no common name. They belong to the 
genus Ephippodonta, a name which is an 
allusion to the unusual way in which the teeth 
of the hinge ride on one another. 
The two species hitherto known were named 
by Professor Ralph Tate, who was a leader in 
the foundation of the Field Naturalists’ Sec- 
tion, in the Proceedings of the Royal Society 
of South Australia; Ephippodonta lunata in 
1886, and E. niacdougalli two years later. 
Ephippodonta are renowned for at least two 
characteristics, both of which are illustrated in 
the new species found by Mrs. J. J. Turnbull, 
an enthusiastic member of the Conchological 
Society of S.A. Unlike most other bi-valves 
they cannot close their valves together so 
that they are extended in one plane, and 
the animal is always exposed on the under 
side. The foot occupies the greater part of 
this area, and it is relatively large, so that the 
animal crawls rather like a snail. The other 
characteristic is that Ephippodonta is com- 
mensal: it lives in association with a prawn 
(Axius plectorhincus) . This prawn makes a 
burrow of mud between and beneath the stones 
of reefs. A yellowish sponge is also usually 
associated with the burrow in which these tiny 
shells live with no harm, and presumably with 
benefit, to the prawn and themselves. 
Above: Ephippodonta macdougalli 
Centre: Ephippodonta turnbullae sp. nov Holotype 
Below: Ephippodonta lunata 
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