120 HANDBOOK OF PROTOZOOLOGY 



crust on the surface or on the half-dry bed of a pool. It is con- 

 sidered, by some investigators, as a variety of E. viridis. 



Euglena deses Ehrenberg (Fig. 40, g). Body about 100 to 

 150 microns in length. Elongated, highly plastic; stigma dis- 

 tinct at the anterior end which is sometimes attenuated. Nu- 

 cleus central; chromatophores hemi-lenticular; numerous small 

 paramylum bodies scattered. Flagellum short. 



Euglena gracilis Klebs (Fig. 40, h). Body about 40 to 45 

 microns long. Cylindrical to elongated oval ; flagellum less 

 than the body length; chromatophores numerous and discoid; 

 nucleus central. 



Genus Phacus Nitzsch. Body greatly flattened; asymmet- 

 rical; body-form constant. Pellicle often with prominent 

 longitudinal or oblique striations. Body structure is similar 

 to that of Euglena. A single flagellum and a stigma. The 

 nucleus is usually located near the posterior extremity. A 

 short cytopharynx; green chromatophores, rounded discoid; 

 paramylum body very conspicuous. Numerous species in fresh 

 water, occur with Euglena. 



Phacus pleuronectes (Ehrenberg) (Fig. 40, i). Short posterior 

 elongation is slightly curved. A prominent fold on the convex 

 side, extending to the middle of the body ;longitudinally striated. 

 One or more circular paramylum bodies. Colorless forms 

 sometimes appear. Body up to 75 microns in length. 



Phacus longicaudus {T>u]a.r6\n) (Fig. 40,7). Body about 85 

 to 100 microns long. Usually twisted with a long caudal pro- 

 longation. Stigma prominent. A large discoidal paramylum 

 body in the center of the body. Pellicle longitudinally striated. 



Phacus pyrum (Ehrenberg) (Fig. 40, k). Length about 40 

 microns. Pyriform with a straight caudal prolongation. Pel- 

 licle with oblique striations. 



Phacus triqueter (Ehrenberg) (Fig. 40, /). Body about 40 

 to 45 microns long. Ovate; with a longitudinal ridge; caudal 

 prolongation is acuminate. Oblique striation distinct. 



Genus Lepocinclis Perty. Body more or less ovo-cylindrical ; 

 rigid with a usually spirally striated pellicle. Often with a short 

 posterior spinous projection; stigma sometimes present. 

 Numerous discoidal chromatophores marginal; paramylum 

 bodies usually large and ring-shaped, laterally disposed. 



