50 



PROTOZOA. 



Section 4. Peritricha. 



Cilia confined to an adoral spiral and a posterior circlet which is not always 

 present. The adoral spiral with the peristomial area is placed at the front 

 end of the body (except in one family). The mouth, anus, and reservoir of the 

 contractile vacuole all open into a depression of the peristome called the vestibule. 

 The peristome and adoral cilia are generally surrounded by a projecting lip-like 

 ridge. 



Fam. 1. Spirochonina. With a peculiar peristomial funnel rolled into a 

 spiral at the front end. Reproduction by budding near the peristome. Attached 



by an adhesive disc at the hind 

 end. Total conjugation between 

 small animals with undeveloped 

 peristome. No. posterior circlet of 

 cilia. Parasitic on the legs of 

 Gammarus, Limnoria, Nebalia. 

 Spirochona Stein. 



771 



FIG. 41. Ciliary apparatus of a Hypotrich Onycho- 

 dromus grandis (from Perrier after Maupas). 

 a adoral membranellae ; b paroral cilia ; c mar- 

 ginal cirri ; d frontal cirri ; e ventral cirri ; 

 / anal cirri ; m preoral undulating membrane ; 

 n nucleus ; v contractile vacuole. 



FIG. 42. a, Aspidisca lyncaster, 

 and b, Aspidisca polystyla dur- 

 ing fission (after Stein). 



Fam. 2. Lichnophorina. Peris- 

 tome and adoral spiral ventral. 

 Hind end as a sucker for attach- 

 ment, and surrounded by the pos- 

 terior circlet. Ectoparasitic on the 

 skin of Medusae, Opisthobranchs, 

 worms, and Asteroids. Liclmo- 

 phora Clap. 



Fam. 3. Urceolarina. Free-swimming, with posterior circlet of cilia, which 

 encloses an adhesive disc ; without peristomial lip. Trichodina Ehrb., ecto- 

 parasitic on the skin of fresh-water and marine animals, e.g., Hydra, Planarians, 

 etc. also endoparasitic in bladder of fishes and Amphibia. Cyclochccta, Jackson, 

 on the surface of sponges, gills of Scorpcena and Trigla, etc.; Trichodinopsis 

 Clap, and L. , in gut and mantle cavity of Cyclostoma. 



Fam. 4. Vorticellina. For the most part attached ; without permanent 

 posterior circlet ; with peristomial lip, which can be closed over the peristome 

 in a sphincter-like fashion ; a large undulating membrane continued into the 

 vestibule. In addition to the adoral zone there is an inner circle of cilia cor- 

 responding to the paroral row of other types ; it extends into the vestibule. 



