370 Ciliophora 



tration, the young parasite develops a functional cytostome, feeds partly 

 on fragments of epithelial cells, and grows to a diameter of 100-I,000[jl. 

 The mature ciliate then drops off the host and encysts. 



Three genera have been referred to this family: Ichthyophthirius Fouquet (83, 145, 

 155; Fig. 7. 21, A-C), Ophryoglena Ehrenberg (155; Fig. 7. 21, D, E), and Proto- 

 phryoglena Mugard (155). 



Family 6. Philasteridae. Members of this family are elongated ciliates 

 with a long and approximately triangular peristomial groove. Although 

 the adoral ciliature is basically "tetrahymenal," the three adoral mem- 

 branes are replaced by three ciliary fields — the deltoid, trapezoid, and 

 falciform fields (Fig. 7. 22, H-J) of Mugard (155). However, the paroral 

 membrane persists as such, extending part way along the right margin 

 of the peristome. Stomatogenesis involves multiplication of basal granules 

 at the jDOsterior end of the paroral membrane. 



The following genera, represented by species in salt or brackish water, are referred 

 to the family: Helicostoma Cohn (102), Paralembus (Lentboides) Kahl (102), Philaster 

 Fabre-Domergue (155; Fig. 7. 22, J), Philasterides Kahl (155; Fig. 7. 22, I), and Porpo- 

 stoma Mcibius (155; Fig. 7. 22, G, H). 



Family 7. Pleuronematidae. The paroral membrane is much enlarged 

 and may extend around the posterior margin of the peristome (Fig. 7. 

 22, A-F). The rest of the adoral ciliature is less uniformly developed and 

 may be represented by a single membrane at the left of the peristome or 

 by a field of cilia in this region (102). In Balantiophorus (216) a con- 

 tinuous membrane extends along the right, posterior, and left margins of 

 the peristome. When fully extended, the membrane forms a sac-like struc- 

 ture covering the peristome except at the anterior end. In certain Pleuro- 

 nematidae, some of the dorso-lateral cilia are thigmotactic and these 

 ciliates often become attached momentarily to a solid surface. One or 

 more long caudal cilia also are often present. 



The Pleuronematidae, which are represented in fresh and salt water, include the 

 following genera: Balantiophorus Schewiakoff (216), Calyptotricha Phillips (102), 

 Cristigera Roux (102; Fig. 7. 22, B), Ctedoctema Stokes (102; Fig. 7. 22, E), Cyclidium 

 Midler (163; Fig. 7. 22, F), Histiobalantium Stokes (102, 158; Fig. 7. 22, D), LarvuUna 

 Penard (102, 165), Pleurocoptes Wallengren (102), Pleuronema Dujardin (102, 158; 

 Fig. 7. 22, A, C). 



Suborder 4. Thigmotrichina 



These ciliates occur mostly in the mantle cavity or on the gills and 

 palps of bivalve molluscs, although species are known also from the 

 mantle cavity of pulmonale snails and from the tentacles of Fhoronopsis. 

 An anterior field of thigmotactic cilia is a general characteristic. A cyto- 

 stome and the adoral ciliature, if present at all, lie in the posterior half 



