390 BIOLOGY OF THE PROTOZOA 



cellidse and are typically attached forms with or without prolonga- 

 tions of the posterior ends in the form of stalks. Such stalks may 

 or may not contain prolongations of the neuromotor apparatus and 

 are correspondingly either highly contractile or rigid. The two 

 other families are represented by very few genera, as follows: 



Family 1. Spirochonidae, Stein.— Here the peristomial area with 

 the adoral zone of membranelles is spirally rolled. Individuals 

 are sessile with or without a stalk. The genera are: 



1. Chilodochona, with stalk and with membrane about the joint 

 of stalk. 



2. SpirocJiona, joint of stalk not provided with membrane, and 



3. Spirochonopsis (questionable). 



Family 2. Lichnophoridse, Biitschli.— The single genus of this 

 family lives an ectoparasitic life usually on the eggs of marine 

 animals {Crepidula, etc.). The organisms are attached to the egg 

 by a disc at the posterior end of the ventral surface; the peristomial 

 region is enlarged and the portion of the body between it and the 

 attaching part becomes drawn out or very much twisted with the 

 activity of the peristomial region bearing the mouth which may turn 

 in any direction. One genus— Lichnojjhora. 



Family 3. Vorticellidse, Ehrenberg, emend Biitschli.— This is not 

 only the largest group of the Peritrichida, but of all ciliates, the 

 accepted classification of the group is the least satisfactory and a 

 revision is greatly to be desired. There are two sub-families — Urceo- 

 larinse and Vorticellinae, the former characterized by the presence 

 of a posterior girdle of cilia which may be transformed into an attach- 

 ing disc, and by the absence of the peristomial trench which is typical 

 of the Vorticellinae. 



Sub-family URCEOLARiNiE.— These are very aberrant Peritrichida 

 and are placed here only provisionally. Particularly questionable 

 forms are those with a complete coating of cilia ( Trichodinopsis) or 

 with spirally wound rows of cilia on the body and a substitution of 

 one or two huge undulating membranes for the adoral zone of mem- 

 branelles ( Hemispira) . The genera provisionally included are : 



1. Tricliodinopsis, with the surface of body covered with cilia. 



2. Hemispira, with row^s of cilia; undulating membrane replaces 

 adoral zone. 



3. Hemispeiropsis, no cilia; two concentric membranes replace 

 adoral zone. 



4. TricJwdina, ectoparasitic; girdle of cilia at posterior end, 



5. Cyclochoeta, parasitic; girdle of erect bristles external to pos- 

 terior cilia. 



Sub-family Vorticellinae, Biitschli.— This large and inade- 

 quately characterized group is further subdivided into three "Tribes" 

 according to the presence of a test or house which is present in 

 Tribe Cothurnina, absent in the other two. The latter are sepa- 



