161 313 
The present material examined by me has proved to be rather 
rich both in individuals and in species but on the whole it is rather 
uniform. Only seldom a single species is predominant in the samples 
such as Cocconeis binotata, Grammatophora oceanica, Mastogloia 
ineequalis, Synedra affinis, but I have not been able to point out 
any difference dependent on variation of the depths which range 
from one to ten fathoms. 
The genera which characterize the material in its entirety are 
Cocconeis and Mastogloia, which occur in numerous samples and 
also often in a great number. 
The following species are especially predominant: Actinocyelus 
subtilis var., Biddulphia pulchella, Climacosphenia elongata, Cocconeis 
binotata, Cocconeis fimbriata, Euphyllodium spathulatum, Grammato- 
phora oceanica, Mastogloia quvinqvecostata, Nav. (Dipl.) Crabro and 
variants, Navicula Lyra, Nav. (Trachyneis) aspera and variants, 
Rhabdonema adriaticum, Rhaphoneis amphiceros and variants, Synedru 
levigata and Triceratium dubiwm. Freshwater forms occur quite 
singly especially in samples from Lem Ngob (from the mangrove). 
Plankton forms are rare and occur only as fragments. I have not 
met with Achnanthes}baccata (compare Flora of Koh Chang, part VI, 
p. (40—41) 258—259). Nearly all the species met with by me are 
recorded from the Tropics and more particularly from the Malay 
Archipelago, which previously has been well examined by eminent 
diatomologists '). 
The marine Diatoms of Siam have a tropical character but do 
not occupy a peculiar position among the other East-Indian marine 
Diatoms such as it might also be anticipated. 
1) I have first been acquainted with the treatise of C. Mereschkowsky: 
On Polynesian Diatoms, St. Pétersbourg 1902, when my manuscript was 
already in press; I have therefore only been able to make use of it in 
noting the geographical distribution of the species stated in my treatise. 
