HI EXPEDITION OF THE " CHALLENGER " 91 



in the North Atlantic. According to Dr. Wallich 

 ("The North Atlantic Sea Bed," p. 157) Globi- 

 gerina is the prevailing form in the deposits 

 between the Faroe Islands and Iceland, and be- 

 tween Iceland and East Greenland or, in other 

 words, in a region of the sea-bottom which lies 

 altogether north of the parallel of 60 N. ; while 

 in the southern seas, the Gloligerince become 

 dwarfed and almost disappear between 50 and 

 55 S. On the other hand, in the sea of 

 Kamschatka, the Grldbigerince have vanished in 

 56 N., so that the persistence of the G-lobigerina 

 ooze in high latitudes, in the North Atlantic, 

 would seem to depend on the northward curve of 

 the isothermals peculiar to this region ; and it is 

 difficult to understand how the formation of 

 Globigerina ooze can be affected by this climatal 

 peculiarity unless it be effected by surface animals. 

 Whatever may be the mode of life of the 

 Foraminifera, to which the calcareous element of 

 the deep-sea " chalk " owes its existence, the fact 

 that it is the chief and most widely spread 

 material of the sea-bottom in the intermediate 

 zone, throughout both the Atlantic and Pacific 

 Oceans, and the Indian Ocean, at depths from a 

 few hundred to over two thousand fathoms, is 

 established. But it is not the only extensive 

 deposit which is now taking place. In 1853, 

 Count Pourtales, an officer of the United States 

 Coast Survey, which has done so much for 





