■490 BIOLOGY OF THE PROTOZOA 



Family 5. Intoshellinidae Cepede 1910. 



1. Skeleton elements in form of collar with 



six spines Genus Intoshellina Cepede 



2. Skeleton in form of circular disc with teeth 



Genus Monodontophrya 

 Vejdowsky 

 Family 6. Hoplitophryidae Cheissin 1930. 



1. Spine simple, projecting from anterior end . 2 

 Spine or skeleton entirely embedded 3 



2. Spine extends beyond anterior end . .Genus Maupasella Cepede 

 Spine ends as an apical point Genus Protoradiophrya Rossolimo 



3. Spine arrow-like, barbed; none in cortex. . 4 

 Body with spines in cortex 5 



4. Spine with simple barb; one row of con- 



tractile vacuoles Genus Mesnilella Cepede 



Spine a tripartite spicule (Fig. 202) . . Genus Hoplitophrya Stein 



5. Body vermiform, not swollen anteriorly 



Genus Radiophrya Rossolimo 

 Body vermiform, much swollen anteriorly 



with radiating spines Genus Mrazekiella Kijenskij 



Order 2. Gymnostomida. 



Key to Sub-orders and Families 



1. Mouth at anterior pole or in immediate 



vicinity Sub-order 1 . Prostomina 



Mouth lateral or ventral 2 



2. Mouth lateral; slit-like or round 



Sub-order 2. Pleurostomina 

 Mouth on anterior half of flat-ventral 

 side Sub-order 3. Hypostomina 



Sub-order 1. Prostomina (Prostomata Schewiakoff). 



1 . Free-living forms 2 



Parasitic forms Family 7. Butschliidae 



2. Mouth region laterally compressed with 



trichites Family 6. Spathidiidae 



Mouth region not compressed, round cross- 

 section, no neck 3 



3. Mouth opens into receptaculum in anterior 



part of body (test-dwelling). . .Family 3. Metacystidae 

 Mouth without receptaculum (not test- 

 dwelling) 4 



4. Mouth at tip of apical mound surrounded 



by circlet of motile organs. . . .Family 4. Didiniidae 

 Mouth otherwise 5 



5. Body covered by ectoplasmic, perforated 



plates Family 5. Colepidae 



Body surface otherwise 6 



6. Body with radially arranged, retractile ten- 



tacles (pseudop.) Family 2. Actinobolinidae 



Bodv without tentacles Family 1. Holophryidae 



