EHIZOPODA. 9 



were formerly placed among the Infusoria. They 

 chiefly inhabit fresh water. 



^. Foramitiifera. — The Foraminifera differ 

 from the ATUoehea in being -usually invested with a 

 calcareous covering or ' shell,' which is sometimes 

 simple, but more frequently consists of an aggre- 

 gation of separate chambers or ' loculi ' commu- 

 nicating with one another by means of minute 

 apertures. In accordance with this character, the 

 name Foraniinifera has been given to the group. 

 The appearance presented by these shells (Jigs. 3, 

 and 4), both as regards outward configuration and 

 internal arrangement, is often exceedingly com- 

 plicated; and, in many cases, the same species 

 presents itself to our notice under a wonderful 

 diversity of forms. Accordingly, those naturalists 

 by whom the Foraminifera were first studied, 

 misled by external characters, assigned these 

 animals a position far higher than that to which 

 their internal structure entitled them. Their true 

 nature was first explained by Dujardin, who 

 showed that the animals inhabiting these cal- 

 careous shells differed in no essential respect from 

 Amoeba or Avcella, and that, like these forms, 

 their bodies were composed of a homogeneous 

 sarcode substance {fig. 3, g). In some Fora- 

 ininifera, this sarcode body is found to assume a 

 bright red colour. The pseudopodia of these 

 animals are usually longer and more slender than 

 those of the Amoehea. 



6. Classification of ForamiaBifera. — By 



D'Orbigny the Forarainifeva have been divided 

 into six " orders," viz. : — 



