POLYMASTIGINA 393 



styles; 1-2 contractile vacuoles in free-living forms; cytostome ob- 

 scure; endoplasm with refractile granules; encystment; in stagnant 

 water or parasitic. 



H. inflata D. (Fig. 168, a). Broadly oval; posterior end truncate; 

 13-25/* by 9-1 5/z; in stagnant water. 



H. intestinalis D. (Fig. 168, b, c). 10-16/x long; in intestine of 

 frogs, also in midgut of Trutta fario and in rectum of Motella tricir- 

 rata and M . mustela in European waters. Morphology (Schmidt, 

 1920). 



H. salmonis (Moore) (Fig. 168, d). 10-12/x by 6-8/*; in intestine 

 of various species of trout and salmon; schizogony in epithelium of 

 pyloric caeca and intestine; cysts; pathogenic to young host fish 

 (Moore, 1922, 1923; Davis, 1925). 



H. periplanetae (Belaf). 5-8 m long; in intestine of cockroaches. 



H. cryptocerci Cleveland (Fig. 168, e). 8-13/t by 4-5. 5/z; in Crypto- 

 cercus punctulatus. 



H. meleagridis McXiel, Hinshaw and Kofoid (Fig. 169, a). Body 

 6-12/x by 2-5/*. It causes a severe catarrhal enteritis in young tur- 

 keys. Experimentally it is transmitted to young quail, chicks, and 

 duckling (McNeil, Hinshaw and Kofoid, 1941). 



H. sp. Hunninen and Wichterman (1938) (Fig. 169, b). Average 

 dimensions 10/x by 5.5m; found in the reproductive organs of the 

 trematode, Deropristis inflata, parasitic in the eel; heavily infected 

 eggs are said not to develop. 



Genus Giardia Kunstler {Lamblia Blanchard). Pyriform to ellip- 

 soid; anterior end broadly rounded, posterior end drawn out; bi- 

 laterally symmetrical; dorsal side convex, ventral side concave or 

 flat, with a sucking disc in anterior half; 2 nuclei; 2 axostyles; 8 

 flagella in 4 pairs; cysts oval to ellipsoid; with 2 or 4 nuclei and 

 fibrils; in the intestine of various vertebrates. Many species. Criteria 

 for species differentiation (Simon, 1921 ; Hegner, 1922) ; cytology and 

 taxonomy (Filice, 1952). 



G. intestinalis (Lambl) (G. enterica Grassi; G. lamblia Stiles (Fig. 

 169, c-g). When the flagella lash actively, the organism shows a slight 

 forward movement with a sidewise rocking motion. The trophozoite 

 is broadly pyriform, not plastic ; 9-20/x by 5-lG>; sucking disc acts as 

 attachment organella; cytoplasm hyaline; 2 needle-like axostyles; 2 

 vesicular nuclei near anterior margin; 8 flagella in 4 pairs; two flag- 

 ella originate near the anterior end of axostyles, cross each other and 

 follow the anterolateral margin of the disc, becoming free; two 

 originating in anterior part of axostyles, leave the body about 1/3 

 from the posterior tip; two (ventral) which are thicker than others, 

 originate in axostyles at nuclear level and remain free; two (caudal) 



