10 PROTOZOA. 



PERFORATA. Soritida. Nummulinida. 



Lagenida. Sorites. Cristellaria. 



OrbuHna ^, , . . -, Nonionina. 



*Lager Globigennida. Nummulina. 



Kotalia. Polystomella. 



Nodosariida. Uvellina. Acervulina. 



Nodosaria Textularia. *Nurnmulites. 



Dentalina.' Globigerina. *Eozoon. 

 .Polytrerna. 

 Carpentaria. 



Bupertia. 



Order IV. RADIO LAEIA. 



POLYCYSTINA. CYTOPHORA. 



Body differentiated into ectosarc and endosarc, and provided 

 with one central capsule or with many [nuclei]. Pseudopodia 

 rod-like, radiating, little disposed to ramify or coalesce. Shells 

 siliceous, external. 



The shells are more or less perforated for the emission of the 

 pseudopodia, and often furnished with radiating spicules ; they 

 are of great variety of form and beauty, and of remarkable com- 

 plexity. They are all oceanic, and, when alive, are of the most 

 brilliant colours ; they appear only to come to the surface after 

 sunset ; but they are believed to exist at all depths in the sea. 

 In the fossil state they largely contribute to form the Tertiary 

 rocks. 



A group of extremely minute forms, "approaching, but in 

 many important points differing from, the Eadiolarians," has 

 been brought to light by the ' Challenger ' expedition. They 

 have received the ordinal name of " Challengerida." They 

 have monothalamous siliceous shells, richly sculptured and 

 filled with a nucleated sarcode. Sir Wyville Thomson consi- 

 ders their position zoologically " not very "far from such forms as 

 Gromia." 



Glaus divides the Radiolaria into five suborders : Heliozoa 

 [here referred to Amoeboidea], Thalassicollea, Polycystinea, 

 Acanthometrae, and Polycyttaria. They have also been di- 

 vided into Collozoa (numerous nuclei) and Collida (a single 

 nucleus). Hackel has two sections Monozoa and Polyzoa ; the 

 former he divides into Ectolithia (skeleton external to the cap- 



