32 



PROTOZOA 



:V 



E. viridis Elir. (Fig. 35). Length .1 mm. or less; body lenticular: 

 often very common in pools, which it may color green. 



E. acus Ehr. Body very long, even filiform, pointed behind; length 

 .18 mm. 



E. deses Ehr. Body elongate, .2 mm. long, with nearly 

 parallel sides: common. 



2. CoLACiUM Ehrenberg. Like Euglena, but usually 

 attached by a short stalk at the forward end to small ani- 

 mals; flagellum present in free-swimming condition, but 

 usually not present when attached : 3 species ; in fresh water. 



C. steini Kent. On IDiaptomus; length .04 mm. 



3. Trachelomonas* Ehrenberg. Like Euglena, except 

 the animal has a brown or colorless shell: numerous species; 

 in fresh and salt water. 



T. lagenella Stein. Shell ovoid or cylindrical and 

 smooth; length .03 mm. 



T. hispida (Perty). Shell ovoid, covered with spines 

 and usually dark brown in color; length .03 mm. 



T. armata Ehr. (Fig. 36). Shell brown, punctate; 2 



rows of spines around aperture and spines often around 



posterior end; length .04. 



4. Phacus Nitzsch. Body somewhat asymmetrical, flattened or 



pear-shaped, with spiral strips; hinder end spine-like; chromatophores 



disc-shaped : 6 species ; in fresh water. 



P. pyrum (Ehrenberg) (Fig. 37). 

 Body top-shaped; length .03 mm. 



P. longicaudus Dujardin. Hinder 



Fig. 35 



Euglena 



viridis 



(Doflein). 



Fig. 36 



Fig. 37 



Fig. 36 — Trachelomonas armata 



(Palmer). Fig. 37 — Phacus 



pyrum (Conn). 



5. Cryptoglena Ehrenberg. Body 

 oval, rigid, with 2 lateral green chromato- 

 phores and an eye-spot: 1 species. 



C. pigra Ehr. Length .015 mm.: in 

 fresh water. 



6. EuTREPTiA Perty. Like Euglena, but with 2 flagella ; body very 

 flexible; chromatophores disc-shaped: 1 species. 



E. viridis Perty. Length .05 mm. : in fresh water. 

 Family 2. ASTASIIDAE. 



Elongated, colorless, more or less amoeboid flagellates without eye- 

 spot and usually with striped membrane; sometimes with an accessory 

 flagellum: 6 genera. 



• See "Delaware Valley Forms of Trachelomonas," by T. C. Palmer, Proc. Acad. 

 Nat. Sci., 1905. 



