460 
BULLETIN OF THE UNITED STATES FISH COMMISSION, 
Key to the marine genera of Vorticellidie. 
Diagnostic characters: Attached or unattached forms of peritrichous ciliates in which the adoral zone seen from above 
forms a right-wound spiral. A secondary circlet of cilia around the posterior end may he present either permanently or 
periodically. 
1. Posterior ciliated girdle permanent around an attaching disk 
2. Posterior ciliated girdle, temporary during motile stage 
3. Body cylindrical: 
(а) With ring of stiff bristles above the ciliated girdle 
(б) Without accessory ring of bristles; with velum 
Body conical; general surface ciliated 
4. No test and no stalk 
6. No test; with stalk containing contractile thread 
6. No test; with stalk but without contractile thread 
7. With a test; with or without a stalk 
8. Individuals solitary 
Individuals colonial; entire colony contractile 
Individuals colonial; parts only of the colony contractile 
3 
4 
Genus Cyclocliseta 
Genus Trichodina 
Genus Trichodinopsis 
Genus Scyphidia 
8 
Genus Epistylis 
Genus * Cothurnia, p. 461 
Genus *Vorticclla, p. 460 
Genus * Zoothamnium, p. 461 
Genus Carchesium 
Genus VORTICELLA (Linnaeus 1767) Ehr. ’38 
(Bell Animalcule Leeuwenhoek 1675; Ehrenberg ’38; Dujardin ’41; Stein ’51; Cl. & Lach. 58; Greet! ’70; 
Biitschli ’88; Kent ’81; Stokes ’88; etc.) 
Medium-sized ciliates of general bell -like form. They may be colorless, or yellow and green 
through the presence of Zoochlorella. When not contracted, the peristome end is widespread, rarely 
narrowed. The adoral zone and peristome agree with the details given in the family characteristics. 
The chief character is the attachment of the posterior end by means of a single, longer or shorter, 
stalk, which contains a highly contractile thread easily distinguished in the living animal. Another 
character is the absence of colony formation. Contractile vacuole, single or double, usually connected 
with a sac-like reservoir. The macronucleus is invariably long and band-formed, with attached micro- 
nucleus. Fresh and salt water. 
