112 



THE INVERTEBRATA 



fr.cir.'^'-zZ 



^u.me. 



^nd.ci. 

 -jyrexi. 



int.u.me. 



f.vac- 

 ahxin-^t: 



se.ct.^-- 



- (^ - -^j-^A n.cir. 



pt.cir. 



Fig. 90. Stylonichia mytilus, in ventral view, x 200. After various authors. 

 ab.cir. abdominal cirri; ad.mae. adoral membranellae ; An. position of anus 

 (on dorsal side) ; An.cir. anal cirri; c.vac. contractile vacuole; c.vac/ accessory 

 canal of the same; end.ci. endoral c\\i2i\ f .vac. food vacuole ;/r.aV. frontal cirri; 

 gu. gullet; int.u.me. internal undulating membrane; lip. projecting lower lip 

 of peristome; mar.cir. marginal cirri; meg. meganucleus; mi. micronucleus ; 

 pre.ci. preoral cilia; pt.cir. posterior cirri; se.ci. "sensory" cilia of dorsal 

 surface ; ii.me. preoral undulating membrane (another undulating membrane 

 is present but is omitted, to simplify the figure). 





Fig. 91. Stylonichia mytilus , from the left side. After Biitschli. 



