504 PROTOZOOLOGY 



ciliation uniform; sometimes longer cilia at anterior or posterior 

 region; eytostome circular, simple, without any ciliary ring 

 around it; cytopharynx with or without trichites or trichocysts; 

 fresh or salt water. Numerous species. 



H. simplex Schewiakoff (Fig. 233, a). Ellipsoidal; 18-20 ciliary 

 rows; ciha uniformly long; eytostome small; cytopharynx without 

 trichocysts or trichites; contractile vacuole and cytopyge pos- 

 terior; macronucleus large, round; 34/x by 18m; fresh water. 



Genus Lagynophrya Kahl. Resembles Holophrya; small elon- 

 gate ovoid to short cylindrical ; one side convex, the other more 

 or less flattened; cytopharynx terminates anteriorly in a small 

 cone-like process found in cross-section, which may or may not 

 be distinct; stagnant fresh or salt water. Several species. 



L. mutans K. (Fig. 233, h). Body plastic; oval to cylindrical; 

 colorless; narrowly striated; oval cone hemispherical without 

 any trichocysts; body about 90^ long, when contracted; about 

 65/i in diameter; among decaying leaves in fresh water. 



Genus Ichthyophthirius Fouquet. Body oval; ciliation uni- 

 form; pellicle longitudinally striated; eytostome at anterior end, 

 with a short cytopharynx with cilia; horseshoe-shaped macro- 

 nucleus; micronucleus adhering to macronucleus, during encyst- 

 ment migrates toward surface of endoplasm; macronucleus 

 undergoes reorganization by discarding small chromatin masses 

 (Haas); multiplication by binary fission during actively motile 

 stage or by multiple division in encysted condition, which pro- 

 duces 200 or more individuals (30-45)U long); conjugation also 

 reported ; parasitic in the integument of various freshwater fishes 

 confined to aquarium or small pond; widely distributed. 



/. multifiliis F. (Fig. 232). 300-800/x long; forms pustules in 

 epidermis or gills; when heavily infected, the host fish suffer 

 fatal effects; Pearson (1932) and Kudo (1934) reported an ex- 

 tensive ichthyophthirius-disease among fishes in large outdoor 

 ponds in Indiana and Illinois. 



Genus Bursella Schmidt. Oval; anterior end broadly and 

 obliquely truncate where a large ciliated groove-like pit occurs; 

 ridges of pit contractile; cilia short; macronucleus, spherical to 

 ellipsoidal; several micronuclei; endoplasm reticulated; with 

 symbiotic algae; ectoplasm with trichocysts; fresh water. 



B. spumosa S. 240-560)u long; freshwater pond. 



Genus Spasmostoma Kahl. Somewhat similar to Holophorya; 



