8 
SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 52 
and pi is the proportion of the ith species. The function was used as a 
measure of species diversity by MacArthur and MacArthur (1961). 
A readable account of its derivation and properties is given by Quast- 
ler (1956). The function takes into account not only the number of 
Fig. 4— H(S) values for the living (top number) and total (bottom number) 
populations in April 1965 ( 0=only 1 species present; - —no foraminifers ; 
paired numbers— replicates) . 
