8 THÉEL, PRIAPULIDS AND STPUNCULIDS OF THE SWEDISH ANTARCTIC EXPEDITION 1901 — 1903. 



Now, we know that the temperature has a definite influence on the distribution 

 of the animals and on the general features of a fauna. The shallow-water fauna of the 

 warm seas presents itself as quite contrary to that of the polar regions, as it is 

 characterised by a girdle of coral-reefs encircling the tropical and subtropical zones 

 and forming the foundation of an unique fauna and flora, rich in forms and quite 

 different from the faunas of northern and southern seas, this girdle of corals being 

 interrupted only at the west coasts of Africa and America. 



The shallow-water faunas, including the littoral ones, of the two polar seas 

 exhibit such a striking resemblance, that the investigator hesitates whether the ani- 

 mals have their cradle in the northern or in the southern cold waters. The literature 

 treating the biology of the polar regions gives sufficient evidence of the truth of 

 this assertion. Every one who has devoted his time to the investigation of the cold 

 faunas, will concur with these views. 



In 1896 Murray 1 sent forth a survey of the deep and shallow-water fauna of 

 the Kerguelen Region of the great southern ocean, and in this he speaks of »iden- 

 tical or closely-allied species which occur in the colder waters of the Northern and 

 Southern Hemispheres, but have not at yet been recorded from the intervening 

 tropical regions.» 



Ehlers, 2 the eminent investigator of the polychcetes, states that no less than 

 five species are bipolär, but have not at yet been recorded from the intervening 

 tropical regions. 



Other scientific men who have had the opportunity of examining collections of 

 arctic and antarctic animals, as e. g. Ludwig 3 and Carlgren 4 assert with regard to 

 the Holothurioidea, Chrinoidea, Ophiuroidea and Actiniaria, that not a single species 

 is common to the two polar-seas, but both of them admit a great similiarity between 

 the two faunas, due to similar conditions of life. In 1886 5 I pronounced the same 

 views. For I wrote : » With respect to the arctic and antarctic regions, the observations 

 hitherto made seem to establish that not a single species of the Holothurioidea is common 

 to both seas. Notivithstanding this, the shallow-ivater fauna of the two regions possesses 

 much the same features.» 



In 1895 the distinguished investigators George Murray and E. S. Barthoun 6 

 write: »These two polar marine floras have been separated as long as there has been 

 climate of any sort on the globe, and out of their poor marine floras there are 54 

 species that occur north and south of the tropical belt, and, so far as we know, not 

 within it. Whether this needs a new cosmical theory to account for it or not we 

 do not pretend to say, but it appears to support Dr. Murray^ other statistics, and 



1 Träns. Roy. Soe. of Edinburgh. Vol. 38. P. II. 1896. 



2 Polychaeten. llamburger Magalhaenische Sammelreise. Hamburg 1897. 



8 Holothurien, Chrinoideen and Ophiuriden. Ilamb. Magalh. Sammelreise. Hamburg 1898 and 1899. 



' Zoantharien. Ilamb. Magalli. Sammelreise. Hamburg 1899. 



■' Report on the Holothurioidea dredged by II. M. S. Challenger 187H — 7(>. P. II. 1886. p. 259. 



(; Phyeologieal Memoirs, being researches made in the botanical department of the British Museum. 

 London 1895. 



