52 



Fresh-water Biology 



RHIZOPODA 



1 — Animal without shell; nucleus present 2 



—With shell 3 



2 — -Web like membrane between pseudopods Hyalodiscus 



— Without membrane between pseudopods. Plasma with fine hyaline rods, Pelomyxa; 

 plasma without hyaline rods (fig. 1) Amoeba 



3 — Pseudopods finger like 4 



— Pseudopods thread like; shell of evident structure with one pseudopod opening, 

 chitinous; without sand grains 7 



4 — Shell chitinous, yellowish, watch glass shape; pseudopod opening on under side. . . .5 

 — Shell structure not homogeneous 6 



5 — With variable number of spines (figs. 2) Centropyxis 



— Without spines though sometimes with scalloped edge (fig. 3) Arcella 



6 — Shell made of sand grains, diatoms, etc. (fig. 4) Difflugia 



— Shell pear shaped, made of 4-sided plates Quadrula 



7 — Shell pear shaped; or spherical; compressed, of spirally arranged plates; mouth with 



toothed plates Euglypha 



— As above but with eccentric mouth Trinema 



— Shell with fine markings, neck bent to one side Cyphoderia 



HELIOZA 



1 — W^ithout outer envelope 2 



— With outer envelope of silicious pieces or shell 4 



2 — Body commonly amoeboid with pseudopods either from all sides or from one place; 



reddish (fig. 5) Vampyrella 



— Body spherical; pseudopods from all sides, flexible with axial fiber 3 



3 — Ectoplasm sharply distinct from entoplasm; many nuclei Actinosphaerium 



— Ectoplasm not sharply distinct; central nucleus (fig. 6) Actinophrys 



4 — Envelope of radiate spines with basal plate Acanthocystis 



— Envelope of silicious shell, with rounded openings ClathruHna 



Plate 21. Protozoans 



1, Amoeba 



2, Centropyxis 



3, Arcella 



4, Difflugia 



5, Vampyrella 



6, Actinophrys 



7, Stentor 



8, Coleps 



9, Holophrya 



10, Colpodium 



11, Chilodon 



12, Loxodes 



13, Lacrymaria 



14, Lionotus 



15, Amphileptus 



16, Dileptus 



17, Halteria 



18, Euplotes 



19, Peranema 



20, Paramcecium 



21, Chilomonas 



22, Frontonia 



23, Trichodina 



24, Stylonychia 



25, Astasia 



26, Carchesium 



27, Epistylis 



28, Vorticella 



Actinophrys, 6 

 Amoeba, 1 

 Amphileptus, 15 

 Arcella, 3 

 Astasia, 25 

 Carchesium, 26 

 Centropyxis, 2 

 Chilodon, 11 

 Chilomonas, 21 

 Coleps, 8 

 Colpodium, 10 

 Difflugia, 4 

 Dileptus, 16 

 Epistylis, 27 



Euplotes, 18 

 Frontonia, 22 

 Halteria, 17 

 Holophrya, 9 

 Lacrymaria, 13 

 Lionotus, 14 

 Loxodes, 12 

 Paramoecium, 20 

 Peranema, 19 

 Stentor, 7 

 Stylonychia, 24 

 Trichodina, 23 

 Vampyrella, 5 

 Vorticella, 28 



