BY A. J. JUKES-BROWNE. 
71 
both edible and pearly (Ostrea and Meleagrina). Lastly, 
some species fix themselves to rocks by one valve and form 
thick foliaceous or spiny shells, 'one valve of which is 
smaller than the other (Chama and Spojidylus ). 
Bivalves differ also very greatly in the way in which the 
two valves are hinged together. In most cases the opposing 
edges are furnished with a set of projections or teeth which 
fit in between one another, and the arrangement of these 
teeth affords a basis of classification into families and 
genera. In some there are a great number of similar 
small teeth, as in the Ark-shells (Area); in others there 
are two or three median teeth with elongate lateral teeth 
on each side, as in the Cockles ( Cardium ) and the genera 
called Mactra and Donax. Others, again, have only 
median teeth, and a few have no teeth at all (as in Anatina) 
or only a spoon-shaped process (as in Mya). 
Bivalves are rather more local in their distribution than 
Univalves, and it is quite possible that some are common 
on the north coast of Borneo which are rare elsewhere. 
This article has been written in the hope that I may 
interest some of the planters, officials, and traders who live 
on and near the seashore in the subject of Marine Mollusca, 
that I may induce them to observe the animals which 
construct all these various kinds of shells, and to collect 
the shells themselves, either for their own interest and 
study or for exhibition in the Bajah’s Museum at Sarawak. 
I shall be happy to correspond with any one who resides in 
Sarawak or other part of Borneo, and would name any 
shells that are sent to me through the Curator of the 
Museum. 
