Q 



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 Trkhodesmium and 

 Heliot rich 1(7)1: 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 Gleve'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, Natiirliche Pflanzenfamilien, I^ 

 1 b, 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. : 



c means pyedomlncuit 



-\- ,, rather common 



r ,, rare 



rr „ vertj rare (only a few specimens seen). 



Bacillariaceae. 

 A. Centricae. 



Coscinodisceae. 



Hyalodiscus Ehbg. 



1. H. sp. 



A very delicate Hyalodiscus without any visible structure is not rare- 

 in the samples. 



2(r) —. 3(r) — 4{rr) — 5 (rr) - (rr) - 7 (rr) — 10 (rr). 



') P. T. Gleve: The Seasonal Distribution of Atlantic Plankton Organisms. 

 Goteborg. 1900, p. 24. [In the list abbreviated to „Atl. Plankt. Organisms ^]. 



