58 MANUAL OF ZOOLOGY. 



garnules and vacuoles. The pseudopodia are derived from 

 the ectosarc alone, the endosarc not passing into them, and 

 they exhibit a circulation of granules along their edges, though 

 this is not nearly so marked a feature as in the case of the 

 Foraminifera. A nucleus and contractile vesicle are also 

 present. The long filamentous pseudopodia of Actinophrys 

 make a decided approach to the Foraminifera, and for this 

 reason the sun-animalcule is sometimes placed with the latter 

 in a single order. 



The Amosbea may be divided into two sub-orders : i. 

 Amoebina, including those forms which have the body naked ; 

 and 2. Arcellina, comprising those in which the body is 

 protected by a carapace. 



CHAPTER III. 

 FORAMINIFERA. 



ORDER III. FORAMTNIFERA. The Foraminifera may be 

 defined as Rhizopoda in which the body is protected by a shell or 

 " test" usually composed of carbonate of lime ; there is no distinct 

 separation of the sarcode of the body into ectosarc and endosarc, 

 and the nucleus and contractile vesicle are both absent. The pseu- 

 dopodia are long and filamentous, and interlace with one another 

 to form a network. 



The Foraminifera are specially characterised by the posses- 

 sion of a " test " or external shell, which is usually composed 

 of carbonate of lime, but is often composed of grains of sand 

 or other adventitious solid particles cemented together by 

 animal matter, or which, as in Gromia, may be simply chitin- 

 ous. (If Lieberkuhnia is to be regarded as a Foraminifer, the 

 possession of a test cannot be looked upon as essential, since 

 this animalcule is naked. The Monera, also, differ from the 

 present group mainly, if not altogether, by their naked and 

 unprotected bodies.) The test is usually composed of an 

 aggregation of chambers or "loculi" (fig. 7, c\ and its walls 

 are usually pierced by numerous pores or " foramina" through 

 which the pseudopodia are protruded ; the place of these 

 being in some forms supplied by the large size of the terminal, 

 or " oral" aperture of the shell (fig. 7, V). The presence or 

 absence of foramina in the shell-walls is believed to constitute 

 a genuine structural distinction, and the Foraminifera may be 



