CHAPTER IV. 



MARCH. 



PARAMECIA— EFFECTS OF SIJXLIGHT— PTERODINA PATINA- 

 CURIOUS TAIL— USE OF A COMPRESSORIUM—INTERNAL STRUC- 

 TURE OF PTERODINA— METOPIDIA—TRICIIODINA PEDICULUS 

 — COTHURNIA— SALPIXA-ITS THREE-SIDED BOX— PROTRUSION 

 OF ITS GIZZARD MOUTH. 



