Chapter 39 

 Order 2 Spirotricha Butschli (continued) 



Suborder 3 Ctenostomata Kahl 



THE ciliates placed under this group are carapaced and com- 

 pressed forms with a very sparse cihation. The adoral zone 

 is also reduced to about 8 membranellae. These organisms are 

 exclusively free living and sapropelic in fresh, brackish, or salt 

 water. 



Posterior half of carapace with 4 ciliated rows on left and at least 2 

 rows on right; with anterior row of cilia on left side near frontal 



edge Family 1 Epalcidae 



Posterior half of carapace with cirrus-like groups on left only, none on 

 right; without frontal cilia 



Long ciliated band extends over both broad sides 



Family 2 Discomorphidae (p. 601) 



Short ciliated band ventral, extending equally on both broad sides 

 Family 3 Mylestomidae (p. 602) 



Family 1 Epalcidae Wetzel 



Genux Epalxis Roux. Rounded triangular; anterior end pointed 

 toward ventral surface, posterior end irregularly truncate; 

 dorsal surface more convex; right carapace with 1 dorsal and 1 

 ventral ciliary row in posterior region; usually 4 (2-3) median 

 teeth; all anal teeth without spine; with comb-like structures 

 posterior to oral aperture; 1-2 oval macronuclei dorsal; contrac- 

 tile vacuole posterior-ventral; sapropelic in fresh or salt water. 

 Many species. 



E. mirahilis R. (Fig. 272, a). 38-45m by 27-30/x; fresh water. 



Genus Saprodinium Lauterborn. Similar to Epalxis; but some 

 of anal teeth (left and right) with spines; sapropelic in fresh or 

 salt water. Several species. 



S. dentatum L. (Fig. 272, b). QO-SOfx long; fresh water. 



S. 'putrinium Lackey (Fig. 272, c). 50ju long, 40ai wide, about 

 15/i thick; in Imhoff tanks. 



Genus Pelodinium Lauterborn. Right carapace with 2 median 

 rows of cilia, its median anal teeth fused into one so that there 

 appear only three teeth. One species. 



P. reniforme L. (Fig. 272, d). 40-50/i long; sapropeUc. 



600 



