INFUSORIA 



59 



1. BuRSARiA 0. F. Miiller. Body large, purse-shaped, obliquely 

 truncate in front; nucleus long', ribbon-like: 1 species; in fresh water. 



B. truncatella Mill. (Fig. 100). Length 1 mm. 

 and more: often between fallen leaves in the 

 water. 



2. Balantidium Stein. Body spindle-shaped, 

 with the oral groove at the apex : 4 species, para- 

 sitic in mammals, amphibians, and worms. 



B. coli St. (Fig. 101). Length .12 mm.: in 

 the large intestine of the pig and man, causing 

 diarrhoea. 



B. entozoon (Ehrenberg). Length .2 mm.: 

 in the large intestine of frogs, toads, and 

 salamanders. 



3. CoNDYLOSTOMA Dujardin. Body rounded or cylindrical, tapering 

 anteriorly with obliquely truncate foi^ard end; nucleus bead-like: 2 

 species, in fresh and salt water. 



C. patens (0. F. Miiller) (Fig. 102). Length .4 mm.; width .10 

 mm.: fresh and salt water. 



Fig. 100 



Bursaria truncatcUa 

 (Conn). 



Fig. 101 



Fig. 102 



Fig. 103 



Fig. 101 — Balantidium coll (Doflein). Fig, 102 — Condsjlostoma patens (Calkius), 

 Fig. 103 — Stentor cocruleus (Doflein). 



Family 3. STENTOEIDAE. 



Body the shape of an elongated funnel and very contractile, the 

 small end of which can be attached; large end truncate, the adoral zone 

 passing around the edge; nucleus usually beaded: 2 genera; in fresh 

 water. 



Stentor* Oken. Fixed or free-swimming; when swimming body 

 is contracted and ovate: 8 species; in fresh water. 



S. cceruleus Ehrenberg (Fig. 103). Body blue; length .25 mm. 



* See "Selection of Food in Stentor coeruleus (Ebr.)," by A. A. Scbaeffer, Jour. 

 Exp. Zool., Vol. 8, p. 839, 1910. 



