46 THE INVERTEBRATA 



Leucochrysis. As Rhizochrysis^ but colourless. 



Silicoflagellata (or Silicoflagellidae). One flagellum; numerous 

 yellow chromatophores ; a lattice-work case of hollow, siliceous bars. 

 Marine, planktonic, e.g. Distephanus (Fig. 38 F). 



Coccolithophoridae. One or two equal flagella; two chromato- 

 phores (sometimes green); a case composed of calcareous plates 

 (coccoliths) or rods {rhabdoliths) enclosing the body. Marine, plank- 

 tonic, e.g. Syracosphaera (Fig. 38 E). 



Order CRYPTOMONADINA 

 Green, yellow, brown, or colourless phytomastigina ; with starch (and 

 occasionally also oil) reserves ; with gullet or with longitudinal groove, 

 without transverse groove; very rarely amoeboid. 



Many of the yellow members of this group live in the resting stage 

 as symbionts in other organisms.^ 



Cryptomonas (Fig. 39 A). Two flagella; two chromatophores, 

 usually green; a gullet. Marine and in fresh waters, 



Chrysidella (Fig. 39 B). Two flagella; two yellow chromatophores; 

 a groove anteriorly. Symbiotic in foraminifera, radiolarians, etc. 



Cyathomonas (Fig. 39 C). Two flagella; chromatophores absent. 

 Holozoic, seizing food by trichocysts in the gullet. In fresh waters. 



Chilomonas. Two flagella ; chromatophores absent ; gullet very deep 

 and narrow. Saprophytic. In foul fresh waters. 



Phaeococcus. Normally in the palmella phase. Marine and in fresh 

 waters. 



Order EU GLENOID I NA 



Phytomastigina which have numerous green chromatophores or are 

 colourless ; with reserves of paramylum and sometimes also oil ; with 

 gullet; with contractile vacuole opening by a ''reservoir", usually 

 into the gullet; without transverse groove; with stout pellicle, 

 usually with metaboly (" euglenoid movement "). 



Euglena (Fig. 39 D, D'). A typical member of the group, with 

 chromatophores ; one flagellum, arising from the bottom of the gullet, 

 double at base, and connected by two rhizoplasts to a basal granule 

 behind the nucleus; pyrenoids present only in a few species; para- 

 mylum reserves ; and contractile vacuole fed by accessory vacuoles. 

 The nutrition is interesting. Some species, at least, can live and 

 multiply, though slowly, with purely holophytic nutrition. None, 

 however, flourish unless some organic matter be present, and the 

 presence of peptones is particularly favourable. If the medium be 



^ Owing to certain features of their nucleus and its mode of division these 

 symbionts have been held to be related to the Dinoflagellata. Their other 

 features, however, are those of the Cryptomonadina. 



