ROMANCE OF DEPTHS OF THE SEA 117 



pharynx or stomach of the Salps which float 

 about in the surface waters. The Coccolitho- 

 phoridae appear to be abundant in the open ocean 

 of the tropical and sub-tropical waters, but they 

 become rare at temperatures below 45 F. They 

 exhibit a great variety of external forms. And, 

 as Dr. Gran writes, notwithstanding their small 

 dimensions these microscopic calcareous creatures 

 occupy a very important place in the economy 

 of the sea, and their shields of lime, which 

 may be met with in geological depths dating as 

 far back as the Cambrian period, show that they 

 have retained their shape practically unaltered 

 through immeasurable ages. 



They are almost entirely oceanic and mostly 

 belong to the warmer seas. In coastal waters, 

 where the salinity is lower, they are scarcer, 

 but the commonest species, the little Pontosphcera 

 huxleyi, has been found even in the Baltic, and 

 there in such immense quantities (five to six 

 million organisms per litre) that the calcareous 

 cells with their strong refraction gave a milky 

 appearance to the waters of the inner parts of 

 the Christiania fiords during the hot summer of 

 1911. Dr. Gran carried on his investigations on 

 these forms from the Canaries to Newfoundland 



