280 



Marine Microbiology 



on punched cards together with sahnity, temperature, latitude, 

 longitude, date, time, depth, etc. Sorting of these cards has just 

 begun, but it has been found that delimiting phytoplankton 

 organisms by salinity and temperature maxima and minima gives 

 a reasonable means of determining "indicator species" and their 

 significance, and thus expressing the ecological picture of the 

 Australasian region with some accuracy. 



A preliminary examination of the data suggests that T-S 

 optima in the Pacific and Indian Oceans differ for certain species 

 in a manner which may indicate different populations of the 



Rhizosolenia sfyliformis 



R. alata 



Mastogloia rostra fa 



Ctimacodium frauenfeldianum. 



Salinity 7oo 



Yig. 2. Salinity-temperature relationships of certain species of diatom 

 phytoplankton in the Indian (left-hand curve) and Pacific Oceans (right- 

 hand curve). 



