INFUSOEIA AND OTHEK ANIMALCULE. 261 



of myriads of animalculee, principally microscopic 

 Foraminifera (Figs. 35 and 36). 



These animalcule, of which, numerous species 

 are still living, secrete a calcareous shell or covering. 



FIG. 35. Foraminifera (magnified). 

 1. Eotalina. 2. Triloculina. 3. Sagrina. 



similar to that of the siliceous infusoria. In spite 

 of their minuteness, these shells offer several par- 

 titions or joints, which render them extremely 

 beautiful ; and as some of them resemble in minia- 

 ture the Nautilus shell, some naturalists have been 

 tempted to class them among the Cephalopoda mol- 

 lusca, of which I have spoken; but very recent 

 investigations invite us to place them as allies of 

 Infusoria. 



" These tiny shells," says Beudant, speaking of 

 Foraminifera, "of which seven to eight hundred 

 fossil species are already known, are found accumu- 

 lated in immense masses in the terrestrial strata, 

 and constitute of themselves enormous stratifica- 

 tions, of which the white chalk, and some of the 



