THE EUROPEAN SEAS. 



135 



fossil, grouped them under sixty genera ; of these 

 forty-four are found in the Mediterranean, contain- 

 ing about 200 reputed species. 



Such low forms of life, hardly coming within the 

 range of man's vision, may seem to some to be not 

 deserving of notice in such a rapid sketch as this 

 is ; but the genera of the Foraminifera have an an- 

 cestry in time, dating back to the earlier ages of 

 the earth's history ; and, minute though they be, 

 their exuviae have helped to build up vaster masses 

 of solid sedimentary strata than any other animal 

 forms. The conditions which these forms indicate, 

 are, therefore, of the highest interest to the geo- 

 logist. 



Selecting those Mediterranean genera which are 

 most prolific, we have — Nodosaria, containing four- 

 teen reputed species, of which three are also British. 

 Dentalina has eight, of which two are British ; Va- 

 ginulina has eight, of which one is common to our 

 fauna. Of Textularice there are fourteen ; Buli- 

 mina, twelve ; Rotalina, sixteen ; Cristellaria, eight ; 

 Nonionina, nine ; Triloculina, eight, of which one 

 is British ; Quinqueloculina, twenty ; of which we 

 have two. 



So far as present observations go, the Bhizopods 

 decrease rapidly both in numbers and in forms, as 

 we proceed from south to north along the European 

 shores of the Atlantic. The British species as yet 

 identified with Mediterranean ones amount only to 

 about six per cent. Of these are Truncatidina lo- 



