FIGURE 4 



FIGURE 3 



FIGURE 4. STEXOSTOMA I.EUCOPS ( AFTER OTt). 



c, cilia, c.p., ciliated pits, cu., cuticula. 



b., brain, com., brain 



commissure, d.o., dish-shaped organs, m., month, ph., pharynx, 

 ph.c, pharyngeal cells, e.c, epithelial cells, in., intestine, w.v.t., 

 water vascular tube, r., rods, p., parenchyme. o.vv., external open- 

 ing of water vascular tube. 



FIGURE 3. STYI.OXYCIIIA MYTILUS (fROM IIARTOG, AFTER LAXg). 



a.c, abdominal cirrhi. an., anus discharging the shell of a Diatom, 

 c.c, caudal cirrhi. c.p., dorsal cirrhi. cv., contractile vacuole, e., 

 part of its replenishing canal, f.c, frontal cirrhi. f.v., food vac- 

 uoles, g., internal undulating membrane. 1., lip. m., mouth or 

 pharynx, mc, marginal cirrhi. N., X., lobes of meganucleus. n, n, 

 micronuclei. o., anterior end. per., adoral membranellae. poc, 

 preoral cilia, p.om., preoral undulating membrane, s.h., sense hairs. 



233 



