Figure 200. Thigmotricha. A, B, Hemispeiropsis comatulae from Antedon {Comatula) 

 mediterranea; C, Hetnispeira asteriasi from Aster/as glacialis ; D-H, Spheiiophrya dosiniae 

 from Dosinia exoleta: D, adult, E, budding individual, F, young individual, G, longi- 

 tudinal section of Sphenophrya on branchial filament, H, transverse section showing ciliate 

 in furrow between branchial filaments; I, J, Gargarius gargarius {Rhynchophrya cristal- 

 Una) from Mytilus edulis ; K-N, series of diagrams showing retrogradation of peristome 

 in Ancistrumidae: K, Ancistruma, L, Proboveria. M, Boveria, N, Hetnispeira. (A, B, 

 after Konig, 1894; C, after Walkngren, 1895; D-H, after Chatton and Lwoff, 1921; 

 I, J, after Raabe, 1935; K-N, after Chatton, 1936.) 



