86 DROPS OF WATER,. 



up a merry dance amongst themselves, advancing 

 and retreating, or gliding past each other with 

 the most graceful movements. These are the 

 most interesting genera of the family Monadina. 



The family Cryptomonadina is distinguished by 

 the individuals having a lorica, or shell, which in 

 some is found to be indestructible by fire. It is 

 either of a box or pitcher shape, and the animals 

 sometimes have more than one proboscis. 



The first genus, Oryptomonas, has some of the 

 individuals green, others brown, and they may be 

 known from the genus Doxococcus by observing 

 that when the little creature is stopped in its 

 rotatory motion by anything in its path, it leaps 

 back suddenly. The individuals of the genus 

 Prorocentrum are only found in the sea, and help 



