46. Forming colonies, usually plant'like, branching 47. 

 Living singly 50. 



47. Animals in a dense cluster, usually at the end of a stem 48. 

 With one animal at the end of each branch 49. 



48. Each animal with a sheath, the collar-like part of which extends beyond 



the animal a distance equal to the body length; stem slender 

 Codosiga Kent 

 Animals without collars; colony with or without a stout stem 

 Anthophysa Bory 



49. Stem branching repeatedly, each time into two, with animals at the tips 



of the branches 



Dendromonas Stein 

 Stems springing from the cup-like sheath of the animal next below 

 Poteriodendron Stein 

 (Stylohryon de Fromentel) 



50. Body shape changing very little; with two or three flagella 51. 

 Body very flexible, varying in shape from oval to elongate; one or two 



flagella 52. 



51. Body spherical to ovate; with one long flagellum and one or two short 



ones 



Monas Ehrenberg 

 Body elongate, with the anterior end truncated or indented; with two 

 nearly equal flagella 



Chilomonas Ehrenberg 



52. Shape very changeable, often putting out pseudopodia, like an amoeba 



Mastigamoeha Schulze 

 Body very flexible, but not putting out pseudopodia 53. 



53. With two unequal flagella, one directed forwards and one trailing; 



body usually widest in the middle 

 Heteronema Dujardin 

 With one long or with one long and one very short flagellum, directed 

 forwards; body very changeable, but in motion usually getting wider 

 towards the rear 54. 



54. Posterior end flattened or truncated when animal is in motion 



Peranema Dujardin 

 Posterior end more or less rounded or tapering 

 Astasia Dujardin 



55. Colonial or permanently attached animals 56. 

 Single, free-swimming individuals 63. 



56. Animal almost surrounded by a transparent or granular sheath; with 



or without a short stem 57. 



No such sheath; with a long stem 60. 



57. Animal trumpet-shaped; with long cilia around the mouth region and 



short cilia over the body 

 Stentor Oken 

 Animal vase -shaped; with cilia around the mouth region but not on 

 the body 58. 



42 



