no PROTOZOA. 



5. Heliozoa, with stiff processes radiating from a spherical body. 

 The outer protoplasm has usually larger vacuoles than the internal 

 portion ; there may be numerous nuclei, and one or more contractile 

 vacuoles. There may be loose flinty needles {Raphidiophrys) ; or rarely 

 a connected framework [ClathruKna] ; or a jelly-like envelope (Hatero- 

 phrys) ; or nothing of the kind (ActinosphiErium). Multiplication by 

 division or by spores. Conjugation occurs. Encystation and spore- 

 making, and in some young forms flagellate phases are known ; the 

 stiff processes become more amoeboid in food-catching. Compared with 

 Lobosa, the Heliozoa are passive. The majority occur in fresh water. 



Examples. — ActinosphiErium, Actinophrys sol (sun-animalcules) ; 

 Raphidiophrys, forming colonies ; ClathruKna, stalked. 



6. FORAMINIFERA. — Predominantly amoeboid forms, with fine 

 branching and interlacing processes issuing from the main mass, which 

 is always within a shell usually calcareous. A nucleus is present, but 

 often multiplies, apparently in association with reproduction. Vacu- 

 oles, contractile or otherwise, seem to be very rare. Conjugation has 

 not been certainly observed. Multiplication may take place by division, 

 but usually by the repeated division of the nucleus and the formation of 

 internal bud-spores. The great majority are marine, occurring at all 

 depths. Those from the depths have usually shells of glued sand ; the 

 limy forms are found at their best in the shallow water of warm seas, but 

 some occur in the open sea, and sink down as they die to form ooze. 

 They are common as fossils from Silurian strata onwards. 



Examples. — Gromia, often in fresh water, with a single opening to 

 its shell ; Microgromia socialis, in fresh water, forming colonies ; 

 Shepheardella, with an opening at each end of a long membranous case ; 

 Miliolina, with a chambered shell simply coiled, and a single aperture ; 

 Lagena, with a simple flask-shaped shell, with diffuse holes for the 

 processes ; Globigerina, a pelagic limy form, with many chambers 

 covered with pores, contributes very largely to the ooze ; Hasiigenna, 

 apparently thriving at great depths, with bubbly protoplasm abundantly 

 overflowing round the shell, which comes to be mternal like a Radio- 

 larian "central capsule" (q.v.); Ammodiscus, from the depths, vrith 

 flinty glued shell ; Halipkysema, a form utilising sponge spicules to 

 cover itself, once mistaken for a minute sponge or for a very simple 

 many-celled animal. 



Most kinds of chalk consist mainly of the shells of Foraminifera 

 accumulated on the floor of ancient seas ; Nummulites and related fossil 

 forms were as large as shillings or half-crowns ; Eozoon, once regarded 

 as a fossil (from pre-Cambrian strata), is more plausibly inorganic. As 

 regards shells and historic sequence, Foraminifera may be grouped in 

 three grades-— (a) with irregularly glued shells ; {b) with regularly glued 

 shells ; [c) with limy shells. 



7. _ Radiolaria.—" Marine Rhizopods, whose unicellular body always 



consists of two main portions separated by a membrane, an inner 



central capsule (with one or more nuclei), and an outer portion, giving 

 off radiating threadUke processes. The protoplasm of the two 'regions 

 is connected by openings in the capsule membrane. The central capsule 

 is partly the general central 'organ' of the Radiolarian cell, partly the 

 special ' organ ' of reproduction, since its protoplasm, along with the 



