278 THE FOEAMINIFEEA 



CHAPTEE XYIII 



THE GEOGKAPHICAL DISTRIBUTION OF FORAMINIFEIIA, 

 WITH EEMAEKS OX THE ACCOMPANYING CONDITIONS 

 OF TEMPEEATFPlE, DEPTH, AND GENERAL ENVIRON- 

 MENT 



FoEAMiNiFEEA are largely influeneed by the tempera- 

 ture of the water in which they live, and therefore it 

 will not be surprising to find that different latitudes 

 have their own peculiar assemblages of species, and 

 that the foraminiferal faunas of the colder regions 

 are in many respects unlike those of the warmer 

 areas. This difference is naturally more noticeable 

 in the case of bottom-living species from^ sJialloio 

 water, for the surface waters of high and low lati- 

 tudes present a wider range of temperature than 

 the water of similar areas at greater depths. Then, 

 again, the distribution of the equatorial and other 

 warm surface currents has a marked influence 

 on the surface-living organisms, as will be seen 

 later on. 



Some genera, and even species of living Fora- 

 minifera, are cosmopolitan, like M'diuJhta aciit'tituluni 

 and Noniouina dej^ressuhi, which are found in almost 

 equal abundance on the shores of the British Islands 

 and in the equatorial waters of the Pacific. Others 

 again are restricted to certain areas, as, for example, 



