40 



KR. BONNEVIE. 



[REP. OF THE "MICHAEL SARS" NORTH 



two, Clio pyramidata and Clio cuspidata, are markedly 

 eurythermal, being distributed throughout the transitional 

 and warm-water zones. The correctness of this opinion 

 is very obviously demonstrated in the two charts, textfig. 

 34 and 35. Several stenothermal species are found scat- 

 tered along the whole southern crossing, but were not 



northern and southern crossings is to be found in the 

 family Cavoliniidae, the distribution of the Limacinidae 

 is seen to be decisive for the richness of the western fauna 

 as compared with the eastern, a difference still greater 

 than that between north and south. (Species 24:15; 

 individuals 5600 : 400). 



10". 



- 1000 n\ 

 3000 m 



% Clio cuspidata 



© Clio pyramidata 

 Fig. 35. 



© Diacria trisvi 



lacria trisvmosa 



taken during the northern crossing (textfig. 34), while the 

 eurythermal species are distributed along the whole route 

 (textfig. 35). To the two eurythermal species mentioned 

 by Meisexheimer must, however, be added a third species, 

 viz: Diacria trispinosa. The Cavoliniidae are represented 

 in the deep-sea fauna by Clio falcata. 



We now turn to a comparison between the eastern 

 half and the western half of the North Atlantic (see table 

 II, p. 46—47). 



While the main difference between material from the 



The occurrence of the species of Limacina in the 

 western half of the ocean only is a fact so obvious (see 

 the chart, textfig. 36) and so peculiar that it may be of 

 interest to analyse it more thoroughly. This analysis will 

 apply especially to the three warm-water species, Limacina 

 bulimoides, L. lesueuri and L. inflata, the occurrence of the 

 northern species, Limacina helicina and L. balea, in the 

 western half finding its explanation in the cold-water 

 currents mentioned above. 



Why should the three warm-water species, so numer- 

 ous in the western part of the ocean, be absolutely absent 



