24 MANUAL OF ZOOLOGY SECT. 



some of these have one large opening, some a number of 

 pores. In certain fresh-water forms, such as Gromia, the 

 shell is chitinoid. In Gromia (Fig. 4, i) the chitinoid shell 

 has a wide mouth through which the protoplasm protrudes 

 to form a layer enclosing the shell and giving off the 

 pseudopodia. 



Little is known of the reproduction of the Foraminifera. 

 But in some a remarkable mode of reproduction has been 

 observed. The protoplasm in the interior of the shell 

 divides up into a number of particles. Each of the bodies 

 thus formed possesses, instead of pseudopodia, a single 

 delicate whip-like appendage the flagellum which lashes 

 to and fro and propels the embryo Foraminifer through the 

 water. Such a flagellum-bearing embryo is termed kflagellula. 



All the Foraminifera, with the exception of Gromia and 

 one or two allied forms, are marine, and the greater number 

 are pelagic i.e. live in the surface waters of the open sea, 

 though they occur also inshore, and at almost all depths. 

 The pelagic Foraminifera are most abundant in warm 

 latitudes, where they occur in enormous numbers. The 

 ocean floor at depths of 500 to 2800 fathoms is covered in 

 many places with a mud-like deposit which effervesces and 

 dissolves when acid is added, and which, when examined 

 under the microscope, is found to consist mainly of the 

 shells of Foraminifera, which must have fallen down from 

 above on the death of the animals. From the name of the 

 genus Globigerina (Fig. 5, 6) which occurs in the 

 greatest abundance in this deposit, it is known as the 

 Globigerina ooze. In the deepest parts of the ocean the 

 Globigerina ooze is entirely absent, the calcareous shells of 

 the Foraminifera apparently becoming completely dissolved 

 before they can reach such great depths. It is interesting 

 to note that similar deposits were formed in previous 



