68 



MANUAL OF ZOOLOGY. 



the Thalassicollida, though to a less extent. Further, through- 

 out the entire network formed by the inosculating pseudo- 



Fig, ii. Morphology of Foraminifera. a Lagena vulgaris, a monothalamous Fora- 

 minifer ; b Miliola (after Schultze), showing the pseudopodia protruded from the oral 

 aperture of the shell ; c Discorbina (after Schultze), showing the nautiloid shell with 

 the foramina in the shell-wall giving exit to pseudopodia ; d Section of Nodosaria 

 (after Carpenter) ; e Nodosaria hispida; fGlobigerina bidloides. 



podia there is a constant circulation of minute protoplasmic 

 granules in different directions. 



The shells of Foraminifera may be classed, according to 

 their composition, in three divisions, termed respectively the 

 " porcellanous," the "hyaline" or " vitreous," and the "aren- 

 aceous." The porcellanous shell is calcareous and quite homo- 

 geneous in its composition, is opaque-white when seen by re- 

 flected light, and is not perforated by pseudopodial foramina. 

 In these forms (&"., Miliola, fig. n, b) the pseudopodia are 

 emitted solely from the mouth of the last-formed segment of 

 the shell. The vitreous shell is also calcareous in composi- 

 tion, but is transparent and glassy in texture, and its walls are 

 perforated by numerous pseudopodial apertures. The aren- 

 aceous Foraminifera (fig. 12) are among the largest of the 

 living types, the test being sometimes half an inch or more 

 in length. In its nature, the test is normally composed of 

 siliceous particles embedded in an apparently chitinous matrix, 

 with a notable proportion of peroxide of iron and a small 

 percentage of carbonate of lime (H. B. Brady). It should be 



