MORPHOLOGY AND TAXONOMY OF THE INFUSORIA 491 



Sub-Order 2. Pleurostomina Schew. 1886; em. Kahl. 



1. Ventral side, with mouth, convex 2 



Ventral side, with mouth, concave 



Family 3. Loxodidae 



2. Mouth an elongated slit Family 1. Amphileptidae 



Mouth round, at base of trichocyst-bearing 



neck Family 2. Tracheliidae 



Sub-order 3. Hypostomina (Hypostomata Schewiakoff) . 



1. Furrow from anterior end to mouth (gut 



parasites) Family 4. Pycnothricidat 



No furrow to mouth 2 



2. Entire body ciliated, or cilia partly reduced 3 

 Cilia confined to ventral side; occasional 



sensory bristles 4 



3. Free-living forms; oral basket present 



Family 1. Nassulidae 

 Invertebrate ectoparasites; no oral basket 



Family 5. Foettingeriidak 



4. Posterior spine on ventral side. .Family 3. Dysteriidae 

 No bristle or spine on ventral side 



Family 2. Chlamydodontidae 



KEY TO GENERA. 



Order 2. Gymnostomida. 



Sub-order 1. Prostomina. 

 Family 1. Holophryidae Perty 1852. 



1 . Spheroidal to oval without definite mouth 



and gullet 2 



Anterior end with distinct mouth, often 

 surrounded by trichites 3 



2. Globular, usually united in chains of four 



Genus Sphaerobactrwn Schmidt 

 Oval, broadly truncate with bowl-like ante- 

 rior pit Genus Bursella Schmidt 



3. Small; mouth polar; refractile; delicate, 



armor-like pellicle 4 



Pellicle not armor-like 6 



4. Pellicle furrowed in spiral lines from ante- 



rior right to posterior left Genus Plants Colm 



Pellicle not spirally furrowed 5 



5. Small, slightly bent ventrally; club-shape; 



no tail cilia; mouth protruding. . .Genus Rhopalophrya Kahl 



Very small, cylindrical, mouth not pro- 

 truding, one long tail cilium Genus Pithothorax Kahl 



(>. Small; flattened laterally; anterior bent 

 ventrally 7 



Small ; not flattened ; no anterior bend .... 8 

 7. No spiral furrows, mouth slit-like; at ante- 

 rior end surrounded by membrane ( Fig. 

 207) Genus Stephanopogon Entz 



Spiral furrows posteriorly to right; mouth 

 sub-apical Genus Platyophrya Kahl 



