HOLOTRICHA 537 



pact group; endoplasm with excretion crystals; 5 preoral ciliary- 

 rows; 130-180/x long; in fresh water. 



Family 8 Parameciidae Grobben 



Genus Paramecium Hill {Paraynaecium M tiller ). Cigar-shaped; 

 circular or ellipsoid in cross-section; with a single macronucleus 

 and 1 to many vesicular or compact micronuclei ; peristome long, 

 broad, and conspicuous; in fresh or brackish water. Several 

 species. 



P. caudatum Ehrenberg (Figs. 22, e; 35; 39, a-e; 48; 74; 245, a). 

 200-260 ju long; with a compact micronucleus, a massive macro- 

 nucleus; 2 contractile vacuoles on aboral surface; posterior end 

 bluntly pointed; in fresh water. The most widely distributed 

 species. 



P. aurelia Miiller (Figs. 77; 79; 245, h). 120-250/x long; 2 small 

 vesicular micronuclei, a massive macronucleus; 2 contractile 

 vacuoles on aboral surface; posterior end more rounded than 

 P. caudatum; in fresh water. 



P. niuUimicronucleata Powers et Mitchell (Figs. 19; 20; 28; 

 29; 245, c). Slightly larger than P. caudatum; 3-7 contractile 

 vacuoles ; 4 or more vesicular micronuclei ; a single macronucleus ; 

 in fresh water. 



P. bursaria (Ehrenberg) (Fig. 245, d). Foot-shaped, somewhat 

 compressed; about 100-200^ by 50-60^; with zoochlorellae as 

 symbionts; micronucleus compact; 2 contractile vacuoles; in 

 fresh water. 



P. putrinum Claparede et Lachmann (Fig. 245, e). Similar to 

 P. hursaria, but a single contractile vacuole and an elongated 

 macronucleus; no zoochlorellae; 80-1 50^ long; in fresh water. 



P. calkinsi Woodruff (Fig. 245,/). Foot-shaped; posterior end 

 broadly rounded; 100-130;u by 50;u; 2 vesicular micronuclei; 2 

 contractile vacuoles; rotation of body clockwise when viewed 

 from posterior end; in fresh and brackish water. 



P. trichium Stokes (Fig. 245, g). Oblong; somewhat compressed; 

 70-100/x long; micronucleus compact; 2 contractile vacuoles 

 deeply situated, each with a convoluted outlet; in fresh water. 



P. -polycaryum Woodruff et Spencer (Fig. 245, h). Form similar 

 to P. hursaria; 70-110^ long; 2 contractile vacuoles; 3-8 vesicular 

 micronuclei; in fresh water. 



P. woodruffi Wenrich (Fig. 245, i). Similar to P. polycaryum; 



