MASTIGOPHOEA 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. EUGLENIDA. 



Large forms with usually a distinct, spirally striped cuticula; 

 1 or 2 flagella present at the forward 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; paramylum, a substance allied to starch, also usually present: 

 3 families. 



Key to the families of Euglenida: 



&! Chlorophyll usually present 1. EUGLENIDAE 



C 2 Chlorophyll absent. 



Z>! Without distinct mouth ; saprophytic 2. ASTASIIDAE 



6 3 With distinct mouth ; holozoic 3. PAEANEMIDAE 



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: 



Q! With one flagellum. 



&! Cuticula elastic, animals more or less plastic. 

 Ci Animal not in a shell. 



h Animal free-swimming 1. EUGLENA 



d 2 Usually attached to other animals 2. COLACIUM 



c 2 Animal in a shell 3. TRACHELOMON AS 



6 2 Cuticula not elastic and animal not plastic. 



c x Chromatophores disc-shaped 4. PHACUS 



c 2 Chromatophores in two longitudinal bands * 5. CBYPTOGLENA 



a 2 With two flagella 6. EUTREPTIA 



1. EUGLENA 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. 



