Tne present work upon the Lamellibranchiata collected by the Danish Ex- 
pedition to Siam forms the first part of a description of all the testaceous Mollusca 
of the Gulf of Siam, which I hope to publish gradually, the description being 
based upon the excellent collections made by Dr. TH. MORTENSEN during the Danish 
Expedition 1899 — 1900. 
I have thought it right to include in the present work all the species which 
have hitherto been recorded from the Gulf of Siam, even although not collected 
by the Danish Expedition to Siam. 
I wish heartily to thank Mr. G. M. R. Levinsen of the Zoological Museum of 
the University of Copenhagen for freely placing the collections of the Museum at 
my disposal; also I am much indebted to my friend at the Zoological Museum, 
Mr. Ap. S. JENSEN, for his unfailing help in searching out material for comparison. 
Unfortunately, our museum in Copenhagen, although excellent in other respects, 
is not rich in Asiatic Mollusca which could have been of use to me for the sake 
of comparison. I was therefore very much pleased, when, during my sojourn in 
London (which I visited before finishing my work), I was able to avail myself 
of the much richer collections in the British Museum of Natural History, owing 
to the ready courtesy and kindness of Mr. EpGar Smitu, to whom I tender my 
heartiest thanks. I am also indebted to Messrs. PH. DAUTZENBERG, Paris, to the 
late Professor Ep. v. MARTENS of Berlin, and to J. Cosmo MELvitt Esq. of Shrews- 
bury for information and intelligence. 
To Dr. Tu. MorreNSEN, who from the beginning has taken a great interest in 
my work, and has always been ready with advice and information, I wish to offer 
my hearty thanks, and also to express my appreciation of the way in which, 
during the Expedition and often under very difficult circumstances, he has got to- 
gether such excellent collections, which have in so many ways enriched zoological 
science with valuable material. 
Copenhagen, December 1908. 
HERM. LYNGE. 
13° 
