220 2 
The sample No.1 is rather rich, but the main part consists of 
detritus and the few present diatoms are partly dead and broken; 
the samples No.2 to No.7 also contain but few Diatoms and Nos. 8 
and 9 nearly none, while they are rich in Trichodesmium and 
Hleliotrichum; they are of a more oceanic character than the other 
samples. On the other hand the sample No. 10 (gathered in March) 
is very rich in Diatoms as well in quality as in quantity, and it 
looks to me as if the coast-water in the Gulf of Siam in the spring 
produces a rich plankton, just as in our more temperate waters. 
With regard to Plankton type in Cleve’s sense, I must admit 
that most of the present samples ought to be classified among 
» Tropical Neritic Plankton‘), except Nos.8 and 9 which belong 
to ,Desmoplankton*, — 
In the list the genera are arranged about as in F. Schiitt: 
Bacillariaceae in Engler & Prantl, Nattirliche Pflanzenfamilien, 1, 
1b, 1896. 
Behind the number of the sample I have indicated in brackets 
the frequency of the species by the ordinary plankton-symbols of 
frequency, Viz.:. 
¢ means predominant 
+ ,  vrather common 
roy ~~ «rare 
ry, very rare (only a few specimens seen). 
Bacillariaceae. 
A. Centricae. 
Coscinodisceae. 
Hyalodiscus Ehbg. 
1. HL sp. 
A very delicate Hyalodiscus without any visible structure is not rare 
in the samples. 
2(r) — 87) — 4(r) — 5(r) — 6 (rr) — Terr) — 10(rr). 
‘) P. T, Cleve: The Seasonal Distribution of Atlantic Plankton Organisms. 
Gdteborg. 1900, p. 24. [In the list abbreviated to , Atl. Plankt. Organisms*“.} 
