508 PROTOZOOLOGY 



Goniis Prorodon Ehrenberg {Rhag ado stoma Kahl). Ovoid to 

 cylindrical; ciliation uniform, with sometimes longer caudal cilia; 

 oral basket made up of double trichites which end deep in ecto- 

 plasm, oval in cross-section; contractile vacuole terminal; macro- 

 nucleus massive, spherical or oval ; fresh or salt water. Numerous 

 species. 



P. discolor (E.) (Fig. 233, I). Ovoidal; 45-55 ciliary rows; 

 macronucleus ellipsoid; micronucleus hemispherical; contractile 

 vacuole terminal; 100-130^ long; fresh water; Kahl (1930) 

 states that it occurs also in brackish w^ater containing 2.5 per cent 

 salt; sapropelic form in salt water is said to possess often long 

 caudal cilia. 



P. griseus Claparede et Lachmann. Oblong; 165-200^ long; 

 fresh water. 



Genus Pseudoprorodon Blochmann. Similar to Prorodon; 

 usually flattened; one side convex, the other concave; ectoplasm 

 conspicuously alveolated; trichocysts grouped; 1 or more con- 

 tractile vacuoles posterior-lateral or distributed, wdth many 

 pores; macronucleus elongate; cytopharynx with trichites; fresh 

 or salt water. 



P. farctus (Claparede et Lachmann) (Fig. 233, w). Ellipsoid; 

 cytostome surrounded by long trichocysts; contractile vacuole 

 posterior, with secondary vacuoles; macronucleus elongate; body 

 150-200^ long; fresh w^ater. 



Genus Placus Cohn (Spathidiopsis Fabre-Domergue; Thoiaco- 

 phrya Kahl). Body small; ellipsoid or ovoid; somewhat com- 

 pressed; pellicle with conspicuous spiral furrows; cytostome a 

 narrow slit at anterior extremity; with strong cilia on right margin 

 of slit; cytopyge a long narrow slit with cilia on both sides; 

 macronucleus ellipsoid to sausage-form; contractile vacuole pos- 

 terior; salt, brackish or fresh water. 



P. socialis (Fabre-Domergue) (Fig. 233, n, o). 40-50^ by 28- 

 32/1, about 22/i thick; salt water; Florida. 



Genus Lacrymaria Ehrenberg. Polymorphic; cylindrical, 

 spindle- or flask-shaped; with a long contractile proboscis; cyto- 

 stome round; ciliary rows meridional or spiral to right; near 

 cytostome a ring-like constriction with a circle of longer cilia; 

 cy topharjmx usually distinct ; contractile vacuole terminal ; fresh 

 or salt water. Numerous species. 



L. olor (M tiller) (Fig. 234, a). Elongate; highly contractile; 



