INFUSORIA AND PORAMINIFEJIA. 75 



jojing a Shrimp or a Mollusc, once in a way, for a hoyme 

 bouche. 



Foraminifera, as a class, differ from Infusoria in this 

 respect, that they are a defined group in themselves, 

 not distinctly connected with any other, but possessing 

 characters which are recognizable and distinguishing. For- 

 merly indeed they were considered as belonging to the 

 very highest class of MoUusca, namely Cephalopoda, for, 

 although very minute, the shells in many instances take 

 very exactly the forms of Nautilus, Ammonite, etc., and are 

 divided like those shells into chambers. They are now be- 

 lieved to be much lower down in the scale, and in recent 

 systems take their humble place among the Tolypi. 



They are all microscopic, glutinous animals, divided into 

 segments, arranged either in a line or rolled spirally ; they 

 are clothed with a shell having numerous orifices, through 

 which pass contractile filaments, which are very long, 

 branched, and used for locomotion. The recent species, 

 although few in our seas, are numerous in warm climates ; 

 yet all those living now are insignificant in numbers com- 

 pared to the enormous multitudes of them which crowded 

 the ancient seas. Large mountains are formed almost en- 

 tirely of their fossil remains. The great stratum on which 



