No. 2.] FRESH-WATER PROTOZOA. 21 



9. Forming branching colonies ii 



Solitary lO 



10. Free, or attached by an attenuated posterior end ; 



moderately flexible; one or two secondary fla- 



gella Monas* 



Free, attenuated in front ; very flexible ; no secondary 



flagellum Leptomonas* 



With the anterior flagellum replaced by a flexible 



tentacle Rhynchomonas* 



11. Many individuals upon the end of each branch 12 



One individual on the end of each branch. .Dendromonas 



12. Stalk short, branching dichotomously once or twice 



Cephalothamnium* 

 Stalk well developed ; the older animals brown, gran- 

 ular Anthophysa* 



13. Colonial 14 



Solitary 15 



14. Lorica horny with pointed posterior end ; colonies 



formed by growth from rim of lorica ; colonies 



free Dinobryon* 



Colonies of numerous individuals in a gelatinous 

 sphere Uroglena^ 



15. Without lorica Ochromonas* 



With horny lorica Epipyxis 



With a shell made of overlapping plates bearing long 



spines Mallomonas* 



Description of Genera. 

 Mastigamoeba F. E. Sch. 



Form amoeboid. Ectoplasm sometimes differentiated. 

 Pseudopodia finger-like to acute, rarely branching. A 

 nucleus and one or more contractile vacuoles present. One 

 prominent flagellum. Upon assuming the free swimming 

 stage the pseudopodia disappear. 

 M. 'reptans Stokes, Fig. 32. 

 M. longiUlum (?) Stokes, Fig. 33, 

 Cercobodo Krass. 



Body spherical to spindle-formed, amoeboid. Two 

 flagella, of which one is trailing. Motion free or creeping 



