MORPHOLOGY AND TAXONOMY OF THE INFUSORIA 513 



Key to Genera 



Family 1. Halteriidae Clap, and Lach. 1859; mod. Kahl. 

 1. Posterior end without thick, dragging 



process . 



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Posterior end with long, thick, retractile, 



protoplasmic process Genus Tontonia Faure-Fremiet 



2. Highly contractile; Sten tor-like; no pre- 



oral adoral zone ?Genus Meseres Schewiakoff 



Body not contractile 3 



3. With equatorial circlet of long bristles or 



cirri Genus Halter ia Dujardin 



Without equatorial circlet of bristles 4 



4. Adoral zone with distinct pre-oral section; 



frontal part of zone surrounds an apical 



projecting process Genus Strombidium 



Clap, and Lach. 

 Adoral zone without special pre-oral sec- 

 tion Genus Metastrombidium 



Faure-Fremiet 



Family 2. Strombilidiidae Kahl 1032. 



One safe genus Genus Strombilidium Schewiakoff 



Family 3. Tintinnidae Clap, and Lach. 1859 (fresh water forms only). 

 Key to Genera of Fresh Water Forms 



1. Tests gelatinous, delicate; more or less 



covered by foreign bodies, etc 2 



Tests firm; pseudochitin; may be covered 

 by nodules or by algae 3 



2. Body with rows of distinct cilia; tests very 



delicate Genus Strombidinopsis Kent 



Body with cilia behind peristome only; 



tests distinct .Genus Tintinnidium Stein 



3. Tests cylindrical, without neck part . Genus Tintinnopsis Stein 

 Tests with definite neck part Genus Codonella* Haeckel 



Family 4. Ophryoscolecidae Stein 1858. 



1. Adoral zone of membranelles only; no 



dorsal zone 2 



Adoral and dorsal zone of membranelles . . 3 



2. Adoral zone in spiral about cytostome; 



macronucleus elongate Genus Entodinium Stein 



Anterior end uniformly ciliated; macro- 

 nucleus spherical Genus Lauierella Buisson 



3. Adoral and dorsal zones at about the same 



level 4 



Dorsal zone posterior to adoral zone 14 



4. Dorsal zone at right angles to long axis of 



the body 5 



Dorsal zone nearly parallel to long axis of 



the body Genus Cunhaia Hasselmann 



5. Forms without skeletal plates 6 



Forms with skeletal plates 7 



fi. Macronucleus beneath dorsal surface of 



the body; straight Genus Eodinium Kof. and MacL. 



Macronucleus beneath right surface; ante- 

 rior third bent ventrally Genus Diplodinium Schuberg 



* See Kofoid and Campbell (1929) for monographic treatment of Tintinnidae. 

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