POL YMASTIGIDA 163 



two from the middle and two from the posterior end of body. 

 Parasites in the intestine of various vertebrates. Several species. 



Giardia intestinalis (Lambl) (Fig. 62, d-f). Body 12 to 18 

 microns long by 6 microns broad. Commensal in the human 

 intestine. 



Genus Trepomonas Dujardin. Body flattened and more or 

 less rounded. Two cytostomal grooves on the posterior half, 

 one on each side. Eight flagella (one long and three short flagella 

 on each side) arise from the anterior margin of the groove. 

 At the anterior end there occurs a horseshoe-like structure, in 

 which two nuclei are located. Marine, parasitic, or coprozoic. 



Trepomonas agilis Dujardin (Fig. 62, g). About 15 microns 

 long. In infusion made from the sea water and once coprozoic(?) . 



Genus Gyromonas Seligo. Body small, constant, flattened; 

 slightly spirally coiled. Four flagella from the anterior end. 

 Cytostome not observed. Fresh water. 



Gyromonas amhulans Seligo (Fig. 62, h). About 15 microns 

 long. 



Genus Trigonomonas Klebs. Body pyriform, but plastic. 

 Cytostome on either side, from the anterior margin of which 

 arise three flagella. Flagella are six in all. The two nuclei are 

 situated near the anterior end. Rotation movement. Holozoic. 

 Fresh water. 



Trigonomonas compressa Klebs (Fig. 62, i). Length about 

 35 microns. Fresh water. 



Genus Urophagus Klebs. Body somewhat resembles that 

 of Hexamitus, but difl^ers from the latter by the presence of a 

 single cytostome, located at the posterior end of the body, 

 where two short processes occur. Holozoic. 



Urophagus rostratus Klebs (Fig. 62, j). About 20 microns 

 long. Free-living. 



Tribe 3 Polyzoa Calkins 



This group includes those Polymatigida which inhabit the 

 intestine of various species of termites, probably as symbionts. 

 The majority are multinucleate. Each nucleus gives rise to a 

 basal body (from which flagella extend), a parabasal body, and 

 an axial filament. Janicki called this complex a karyomasti- 



