

During the time from the 22th of Dec. 1899 to the 21st of March 1900 Dr. Tu. 

 Mortensen made a series of collections in the eastern part of the Gulf of Siam , from 

 Koh Kong to Koh si Chang. Researches were made only from the coasts out to the depth 

 of about 30 fathoms. The most important localities were the following: 



The sound between Koh Chang and the mainland: the bottom being deep soft 

 mud, very few animals were found there , but at the coasts (Lem Ngob) a varied fauna 

 occurred, also Nudibranchiata, partly (Doriopsis) on the flat muddy shore, which was dry 

 at low water, partly (Idalia) on the stones and rocks covered with algæ (Acetabularia) and 

 oysters. 



On the N., S. and W. coast of Koh Chang several Nudibranchiata were found on 

 old coral-blocks at a depth of about 1 fathom (Chromodoris histrio, Phyllidiella nobilis, 

 Ph. pustulosa). 



At Koh Mesan and Koh Kam a very rich fauna occurred at a depth of ca. 5 

 fathoms: Echinoderms, Crustaceans, Mollusca etc.; the bottom was sand with algæ and 

 phanerogamous plants (Halophila). A noticeable feature in this fauna made the numerous 

 specimens of Philine quadripartita. 



At Koh Chuen and Koh Kram some places at a depth of c. 30 fathoms gave a 

 very rich harvest of Gorgonids, Echinoderms, Mollusca etc. The bottom was hard with 

 small stones. 



A little S. of Koh Tulu a single Nudibranch (Thordisa maculigera) was taken at 

 a bottom of sandy mud with enormous numbers of dead shells, at a depth of about 10 

 fathoms. Off Tung Kaben another Nudibranch (Melibe bucephala) was taken at a bottom 

 of sandy mud overgrown with the above named phanerogamous plant, Halophila, at a 

 depth of about 6 fathoms. W. of Koh Kut, at a depth af about 15 fathoms, soft mud, 

 some specimens of Philine quadripartita were found. 



On floating Sargasso were found an Aplysia and a Plakobranchus. 



D. K. D. Vidensk. Selsk. Skr., 6. Rmklte, naturvidens!;, og mathem. Afd. XII. 2. 0( 



