EIITZOrODA. 



183 



by surrounding and transporting into the interior of the body small 

 vegetable organisms '. Bacillaria. Among the shell-bearing forms, 

 the reception and digestion of food takes place outside the shell in 

 the peripheral threads and networks of sarcode ; for each spot on the 

 surface can for the time being assume the functions of mouth, and 



v FIG. 122. Rotalia venda (after M. Schultze), with a DIaton. taken in tha network of 



Pseudopodia. 



also of anus, by rejecting the undigested remnants. The Rhizopoda 

 live for the most part in the sea, and contribute by the accumulation 

 of their shells to the formation of the sea sand, and even to the 

 deposition of thick strata. An innumerable quantity of fossil forms 

 from various and very ancient formations are known. 







