72 HISTORICAL PALEONTOLOGY. 



Foraminifera. We have had occasion before to speak of these 

 animals, and as they are not conspicuous or commonly-known 

 forms of life, it may be well to say a few words as to the 

 structure of the living representatives of the group. The 

 Foraminifera are all inhabitants of the sea, and are mostly of 

 small or even microscopic dimensions. Their bodies are com- 

 posed of an apparently structureless animal substance of an 

 albuminous nature ("sarcode"), of a gelatinous consistence, 

 transparent, and exhibiting numerous minute granules or 

 rounded particles. The body-substance cannot be said in 



Fig. 25. The animal of Nonionina, one of the Foraminifera, after the shell has been 

 removed by a weak acid; 6. Gromia, a single-chambered Foraminifer (after Schultze), 

 showing the shell surrounded by a network of filaments derived from the body substance. 



itself to possess any definite form, except in so far as it may 

 be bounded by a shell; but it has the power, wherever it may 

 be exposed, of emitting long thread-like filaments ("pseudo- 

 podia"), which interlace with one another to form a network 

 (fig. 25, b). These filaments can be thrown out at will, and 



