262 UNIVERSITY OF COLORADO STUDIES 



With or without shells, with pseudopodia lobose, finger-like or rayhke and some- 

 times anastomosing, with or without axial supports (Class Sarcodina) . i. 

 Small forms provided with one or more flagella; often forming colonies (Class 



Mastigophora) 5- 



With cilia during embryonic and adult life, or (in Subclass Suctoria) in embryonic 

 life only (Class Infusoria) 10. 



1 . Without shells. Pseudopodia lobose or sharp-pointed, sometimes branched (Family 



Amcebidce) 2. 



With membranous shells with which may be incorporated foreign materials. Pseu- 

 dofMDdia lobose or short-pointed, often branched (Family ^rcc//«itE) . . 3. 

 Shells of plates of chitin or silica, sometimes spined. Pseudopodia sharp-pointed, 

 often branched but not anastomosing (Family Euglyphidce) .... 4. 



2. Body of comparatively large size; pseudopodia finger-like or lobose (very abundant) 



Amoeba proteus Leidy 



3. Shell oval or pear-shaped, sometimes with a short neck and broadly expanded 

 fundus with or without spines, composed mainly of sand-grains 



Difflugia pyriformis Perty 

 Shell usually of some shade of yellow or brown, about one -half as high as broad, 

 the character of the surface varied; mouth circular, in the center of the ventral 



surface Arcella vulgaris Ehr. 



Shell a delicate, transparent membrane, exceedingly flexible; endoplasm colorless 

 (very abundant) Cochlipodium bilimbosum Leidy* 



4. Shell composed of oval plates overlapping each other and arranged in regular rows 

 producing the appearance of hexagonal areas; spines often present 



Euglypha alveolata Duj. 

 Body inclosed within an elongated, chitinous shell; fundus rounded, oval extremity 

 narrower and obliquely truncate Trinema enchelys Leidy* 



5. Flagella one or two, at the base of which is a mouth ; often possessing chlorophyll 



(OTdei Euglenida) 6. 



Plantlike flagellates; flagella two; body elongate-oval, anterior margin with a 

 prominent liplike projection; endoplasm usually including dark -colored corpuscles 



Chilomonas paramaecium Ehr. (Order Phytoflagellidd) 

 Body with two transverse furrows; furrow extending wholly round body (Order 

 Dinijerida or Dinoflagellata) Gymnodinium sp.* 



6. Elongated forms usually with a single flagellum; pigment spot and chlorophyll often 



developed (Fam. Euglenidce) 7- 



Body elongated but plastic, with no coloring substance; flagellum single; length 



of extended body 3oh3o m Astasia trichophora Ehr. 



Body persistent in shape and plastic; pharynx distinct; oval, somewhat flattened; 



flagella two; length of body 22 m Entosiphon sulcatus Duj.* 



Persistent in shape; flagella two, the traihng one very short; ovate, the anterior 

 border acutely rounded, the posterior truncate; length of body 12 m 



Notosolenus opocamptus Stokes* 



7. Body elongate, changeable in form; endoplasm usually bright green in color; 

 eye-spot usually present; flagellum single 8. 



