PROTOZOA. 



Order III. FOKAMINIFEKA. 



POLYTHALAMIA. EETICULARIA. ACYTTARIA. HOMOGENEA. 

 THALA.MOPHORA. 



Homogeneous, nearly structureless animals, without a central 

 capsule or a contractile vacuole, generally provided with a par- 

 tially enclosed calcareous shell, with or without a nucleus (or 

 nuclei). 



Locomotion is performed by extending portions of the sur- 

 face ; these are capable of multiplying themselves and coalescing 

 whenever they come in contact. These pseudopodia also act as 

 prehensile organs. The shell may be either simple or divided by 

 septa, into chambers, and is often of extraordinary complexity ; 

 occasionally, as in Lituolidce, it is partially composed of fine sand 

 agglutinated together. In Hyperammina it is almost entirely 

 composed of silica. The shells are extremely liable to vary, 

 according to age and locality : the more simple have only the 

 terminal aperture [Imperforata] ; in the Foraminifera proper 

 [Perforata] the shell is pierced by numerous pores, through 

 which the pseudopodia are emitted. 



The complex forms of their shells are said by Hackel to be 

 " traceable to the active agency of the formless albuminous com- 

 binations of protoplasm," the " results of inherited adaptation" 



The Foraminifera are marine, and are amongst the earliest 

 forms of life ; the chalk formations and nummulitic limestones 

 are almost entirely composed of their shells, and much of the 

 Atlantic bed is covered with an ooze largely composed of Globi- 

 fferina-shells, which, beyond a depth oi' 2400 fathoms, are sup- 

 posed to pass gradually by their decomposition into the red clay 

 which covers many thousand square miles of its bottom. In a 

 living state it is believed they may be found at all depths. They 

 are mostly very minute. 



Eozoon is the oldest known fossil. ParJceria, another fossil, is 

 comparatively of large size (three inches in circumference). 

 Eupertia is a sessile form from the Greenland seas. Many forms, 

 however, are now said to be Algae (e. g. Ovulites, Dactylapora, &c.). 



IMPERFORATA. Miliolidce. Lituolidcs. 



r, ..j Miliola. Hyperammina. 



ftvmtftfe. Orbitulites. Spirillma. 



Gromia, Cornuspira. Lituola. 



Lieberkuhnia. *Parkeria. 



