MASTIGOPHORA 31 



Family DISTOMIDAE. 



Flagella in two symmetrical groups, with a mouth at the base of 

 each: 2 genera. 



Hexamitus Dujardin. Body ovate, with 2 to 4 flagella at forward 

 end and hinder end prolonged into 2 thread-like processes: 3 species; in 

 fresh water, also parasitic in intestine of amphibians. 



H. inflatus Duj. (Fig. 34). Posterior processes not close together; 

 length .027 mm. 



Order 7. ETJGLENIDA. 



Large forms with usually a distinct, spirally striped cuticula; 



1 or 2 flagella present at the foi^ard end, with a so-called 

 pharynx at their base and a contractile vacuole opening into the 

 pharynx; frequently colonial and usually colored by chromatophores 

 in which 1 or more deeply staining bodies, the pyrenoids, may be 

 present; paramjium, a substance allied to starch, also usually present: 

 3 families. 



Key to the families of Euglenida: 



©1 Chlorophyll usually present 1. Euglenidae 



02 Chlorophyll absent. 



6i Without distinct mouth ; saprophytic 2. Astasiidae 



6j With distinct mouth ; holozoic 3. Paranemidae 



Family 1. EUGLENIDAE. 



Body spindle or pear-shaped with usually a single flagellum; chloro- 

 phyll, pyrenoids, and paramylum and an eye-spot almost invariably 

 present; contractile vacuole or vacuoles open into a reservoir which 

 opens into the pharynx; nutrition mostly holophytic, in some cases 

 saprophytic: 6 genera. 



Key to the genera of Euglenidae : 



Oi With one flagellum. 

 6i Cuticula elastic, animals more or less plastic. 

 Ci Animal not in a shell. 



di Animal free-swimming 1. EUGLENA 



dz Usually attached to other animals. . ." 2. Colacium 



Ca Animal in a shell 3. Trachelomonas 



62 Cuticula not elastic and animal not plastic. 



Cj Chromatophores disc-shaped 4. Phacus 



C2 Chromatophores in two longitudinal bands 5. Cbyptoglena 



Oj With two flagella 6. Eutreptia 



1. EiTGLENA Ehrenberg. Large spindle-shaped flagellates with 

 spirally marked cuticula; 1 flagellum, at the base of which are the 

 pharynx, eye-spot, and contractile vacuole; color usually green or 

 red, a few being colorless: species numerous; in fresh and brackish 

 water. 



