184 



PROTOZOA. 



Order 1. FORAMINIFERA.* 



Rhizopoda, either naked or with a shell, the shell almost invariably 

 calcareous and usually pierced with fine pores for the exit of the 

 pseudopodia. 



Only in rare cases, for instance Nonionina and Polymorphina, is 

 the shell substance of a silicious nature; in all other forms it is 





PIG. 123. Mil tola tenera, with network of pseudopodia (after M. Schultze). 



membranous or consists of a calcareous deposit in a basis of organic 

 matter. The shell is either a simple chamber, usually provided with 

 a large opening, or is many chambered, that is, is composed of 

 numerous chambers arranged upon one another according to definite 

 laws. The spaces of these chambers communicate by means of narrow 



* Besides D'Orbigny, Max Schultze, 1. c., compare W. C. Williamson. " On the 

 recent Foraminifera of Great Britain." London, 1S58. Carpenter. -'Introduc- 

 tion to the Study of the Foraminifera," London. 1S62. Reuss. '-Entwurf einer 

 system. Zusammeristellung der Foraminiferen," Wien. 1861. 



