20 



CLASS I 



PROTOZOA RH I ZO L'GIM 



tests consist of minute grains of sand, often intermingled with particles of 

 lime and other foreign matter, the particles being held together by a silicious 

 or argillaceous cement. The tests are unilocular or multil octilar, occasionally 

 attain considerable size, and are either imperf orate (Fig. 5, A), or, in addition 

 to the either simple or sieve-like principal apertures, are punctured by 



FIG. 5. 

 A, Section through an iniperforate arenaceous 



Roeni.) 13, Section through a perforate arenaceous 

 test showing coarse tubuli, highly magnified (Ple- 

 i 'jibbosum, d'Orb.) 



FIG. 



tion of vitreous perforate test with fine 

 tubuli (Nodosaria rapa, d'Orb.) B, Portion of 

 periphery, and section of a vitreous perforate test 

 with coarse tubules less closely set together 

 (Globigerina conglomerates, Sch wager). 



tubules, through which the pseudopodia are emitted (Fig. 5, B). Calcareous 

 tests are also sometimes (Miliolidae, Textularidae) encrusted with agglutinated, 

 compactly cemented sandy particles, and hence consist of an interior calcare- 

 ous, and an exterior sandy-silicious layer (Fig. 6). The greater number of 



FIG. 



Clii,i.'ii-nmmina textulariformis, 

 Holier, sp. Perforate calcareous 

 test invested with arenaceous 

 envelope. % (after Moller). 



FIG. S. 



OpercuKna complanata, Bast. Miocene ; Bor- 

 deaux, a, natural size ; b, median longitudinal 

 section ; c, transverse section, greatly enlarged. 



Lam. Vitreous perforate 

 test with spur-like sup- 

 plemental skeleton tra- 

 versed by canals. 



Foraminifera, however, secrete tests composed of carbonate of lime, which 

 may be either porcellaneous and iniperforate, or vitreous and perforate in 

 structure. In the first class (Imperforata) the shell is homogeneous, and 

 appears in reflected Kght as an- opaque mass (Fig. 4) ; in the second (Perforata) 

 it is lustrous, transparent, and perforated by numerous fine tubules which 

 pass through the walls radially. These tubules, which are visible on the peri- 



