Foraminifera. J31 



pseudopodia serve for obtaining food and for locomotion. QALLEET 

 Ihere are no definite tissues, nor any separate body - cavity, ^- 

 and all the processes of life, such as digestion, excretion J^^m^' 

 respiration, etc., are carried on by the undifferentiated sarcode L?fc*" • 

 or protoplasm. Further, the sarcode, in the case of the Fora- 

 minifera, forms solid, hard shells, or tests, which in a few cases 

 are of a chitinous or horny character, but more usually are of 

 carbonate of lime, or of minute particles of sand or other foreign 

 materials, neatly cemented together. 



The shell, or test, in its simplest form, may consist of a single 

 spherical or oval cliamber of microscopic dimensions, with a definite 

 aperture and walls which may either be perforated with minute 

 tubules or non -perforate. The animal sarcode fills the chamber 

 and sends out its pseudopodial extensions through the opening, and 

 also, in the perforate forms, through the minute tubules of the wall, 

 in the form of long, delicate threads. In the less simple forms 

 the test is divided by septa into a variable number of chambers, 

 or there is a succession of chambers attached together and com- 

 municating by their apertures with each other. It is from the 

 shape of the individual chambers, and the mode in which they are 

 attached together, either in straight lines, spirals, concentric rings, 

 alternating straight or spiral rows, or irregular aggregations, 

 that the marvellous variety of form of the foraminiferal test 

 results. 



The greater number of Foraminifera possess tests of carbonate 

 of lime, and these may be either porcellaneous and imperforate, 

 or glassy (hyaline, vitreous) and perforate. In the porcellaneous 

 group the test is compact, opaque-white, and without minute 

 pores or tubules, so that the pseudopodia can only pass through the 

 oral aperture. In the glassy-porous group the shell is translucent 

 and shiny, and it is penetrated by numerous minute canals. In 

 certain of these porous shells there is also a system of coarse 

 anastomosing canals in the septa, or in the median plane of the 

 spiral folds, which do not connect with the pores ; and in many 

 of the more complex forms there is an intermediate skeletal 

 layer. The "arenaceous" tests are built up of sand -grains, 

 minute shells, sponge - spicules, and other extraneous par- 

 ticles cemented by lime or siliceous materials. These shells 

 may be either compact or with perforate walls. In some 

 instances the wall of the test consists of an inner calcareous 



