MORPHOLOGY AND TAXONOMY OF THE INFUSORIA 489 



Order 1. Astomida. 



Key to Families 



1. Without dimorphic nuclei Family 1. Opalinidae 



With dimorphic nuclei 2 



2. Skeleton organs or attaching structures 



absent 3 



Skeleton structures or attaching organs 

 present 4 



3. Contractile vacuoles absent or scattered; 



macronucleus spheroidal, elongate or 



branched Family 2. Anoplophryidae 



Contractile vacuole absent; macronucleus 



fragmented Family 3. Chromidinidae 



4. Vacuole a dorsal canal Family 4. Haptophryidae 



Vacuoles in rows or distributed 5 



5. Without supporting elements in cortex 



Family 5. Ixtoshellinidae 

 With supporting elements in cortex 



Family 6. Hoplitophryidae 

 Family 1. Opalinidae Claus. 



1. Form cylindrical; circular in cross-section . 2 

 Form flattened ; ellipsoidal in cross-section . 3 



2. With two similar nuclei Genus Protoopalina Metcalf 



With many similar nuclei Genus Cepedea Metcalf 



3. With two similar nuclei Genus Zelleriella Metcalf 



With many similar nuclei Genus Opalina Purkinje 



Family 2. Anoplophryidae Cepede 1910. 



1. Body without anterior sucker 2 



Body with anterior sucker 8 



2. Without anterior protoplasmic process. ... 3 

 With anterior protoplasmic process 7 



3. Cilia in longitudinal, not spiral, lines 4 



Cilia in spiral lines Genus Orchitophrya Cepede 



4. Contractile vacuoles present 5 



Contractile vacuoles absent Genus Meta/phrya 



5. Contractile vacuoles multiple, in rows 



Genus Anoplophrya Dujardin 

 C. V. single, posterior 6 



6. Body pyriform; C. V. sub-terminal . Genus Kofoidella Cepede 

 Body ellipsoid; C. V. terminal Genus Perezella Cepede 



7. C. V. single; macronucleus spheroidal 



Genus Herpetophrya Siedlecki 

 C. V. numerous, in one row; macronucleus 



elongate Genus Biltschliella Awerinzew 



8. Macronucleus spheroidal Genus Cepedella Poyarkoff 



Macronucleus branched Genus Khizocaryum Caul, et Mes. 



Family 3. Chromidinidae Cheissin 1930. 



One genus only, Chromidina (including Opalinopsis) 

 Family 4. Haptophryidae Cepede 1923. 



1. Body without sucker; with hook. . .Genus LachmaneUa Cepede 

 Body with sucker ; with or without hooks . 2 



2. Body with sucker and two hooks. . .Genus Steinella Cepede 

 Highly developed sucker ; no hooks or skel- 

 eton Genus Haptophrya Stein 



