MORPHOLOGY AND TAXONOMY OF THE INFUSORIA 519 



Family 1. Oxytrichidae Ehr. 1838. 



13. Small fresh water forms; long, separated 



ventrals, no special frontal cirri; dorsal 



bristles high Genus Ballad ina Kowalewski 



Form and structure otherwise 14 



14. With long tail, highly contractile marine 



forms (Fig. 208) Genus Epiclintes Stein 



Form different; if tailed, then moderately 

 contractile — fresh water 15 



15. Commensal on different species of Hydra 



Genus Kerona Ehr. 

 Free-living — not commensal 16 



16. More than 2 ventral rows of cilia 17 



One to 3 ventral rows of frontals not dis- 

 tinct Genus Holosticha (in part see 20) 



Wrzesniowski 



17. Three ventral rows; frontal rows not much 



enlarged Sub-genus Trichotaxis Stokes 



More than 3 ventral rows; 3 frontal cirri 

 strongly marked 18 



18. Ventral cirri all in rows (1 to 6) 19 



Ventral cirri united in groups 21 



19. Ventral cirri in 4 or more rows Genus Urostyla Ehr. 



Ventral cirri in 1 to 3 rows or absent 20 



20. Ventral rows absent; marine form with 



narrow neck-like peristome Genus Trachelostyla Kahl 



Ventral rows 1 to 3 in number, 3 frontals 



distinct Genus Holosticha (in part see 16) 



21. Ventral cirri in 1 to 3 rows; post oral and 



posterior groups of small cirri in addition 22 

 Complete ventral rows absent 26 



22. Complete rows run parallel with long axis . . 23 

 Complete rows run diagonally from ante- 

 rior right to posterior left 25 



23. One complete row on left, 2 on right; trans- 



verse cirri in complete rows Genus Onychodromopsis Stokes 



The 2 right transverse cirri well behind the 

 3 left 24 



24. On each side, one complete ventral row 



Genus Allotricha Sterki 

 Two complete ventral rows on right . Genus Pleurotricha Stein 



25. One diagonal ventral row running close to 



the transverse row (Fig. 210) .. . .Genus Gastrostyla Engelmann 

 Adoral zone placed laterally; ventral rows 

 short, within or just beyond peristome 



Genus Gonostomum Sterki 



26. Posterior end may be drawn out in long 



thin stalk Genus Ancistropodium 



Faure-Freinid 

 Posterior end never drawn out in long thin 

 stalk 27 



27. 12 to 15 powerful frontal cirri, 4 macro- 



nuclear parts Genus Onychodromus Stein 



8 frontal cirri in 3 groups ; macronucleus in 

 2, rarely in 1 or 4 parts 28 



