436 THE ALGAE 



water species (e.g. Cystoseira) to occur in south-west Ireland and 

 on the coast of Cornwall. In the southern hemisphere Bennett and 

 Pope (1953) h^ve studied the biogeographical provinces of tem- 

 perate Australia and they consider that four components can be 

 recognized : 



(a) tropical, the main species occurring north of 26° south; 



{h) warm-temperate; 



{c) cool-temperate; 



{d) universal. 

 This classification is possibly too broad because Hormosira is in- 

 cluded under Universal. As a result of this work they suggest that 

 the average winter sea temperature of 10° C, which Stephenson 

 regarded as the limiting value between warm and cool temperate, 

 may need raising since the Victorian flora is definitely cool tem- 

 perate and the average winter temperature is 11 -8° C. In the case 

 of such a large continent as Australia there is considerable variation 

 around the coasts. The marine fauna and flora fall into a number of 

 provinces which agree very closely with those established by 

 Ferguson- Wood in his study of Australian Dinoflagellates. In 

 adjacent New Zealand there is a strong endemic element but Aus- 

 trahan and sub-Antarctic components are also represented, the 

 latter being found also in South Africa (see Fig. 229). 



So far it is clear that only preliminary studies have been made of 

 this aspect of phycology. Uniformity of approach would, however, 

 seem to be important and so in in 1946 the writer proposed a 

 general scheme of floristic elements as follows : 



Arctic Antarctic 



Sub-Arctic Sub-Antarctic 



Boreal Arctic Austral Antarctic 



Cold Boreal Atlantic Cold Austral Atlantic 



Cold Boreal Pacific Cold Austral Pacific 



Boreal Atlantic Boreal Pacific Austral Atlantic Austral Pacific 



North sub-tropical North sub-tropical South sub-tropical South sub-tropical 



Atlantic Pacific Atlantic Pacific 



Tropical Atlantic Tropical Pacific 



Pan tropical Cosmopolitan 



Caribbean Arabian 

 Indo-Pacific 



In this classification Boreal and Austral both represent warm 

 temperate components. This classification has since been used as a 

 basis for the analysis of the marine algal flora of Jamaica: 



