EPITHELIUM OF TURBELLARIA 259 



ABBREVIATIONS 



6, basement incinhrune o, outer muscle layer 



c, cilia p, wall of pharyngeal sack 



e, epithelium />i, cavity of pharyngeal sack 



ex, excretory duct s, cavity of seminal vesicle 



i, inner muscle layer Si, remnant of epithelium of seminal 



m, muscles of seminal vesicle vesicle 



n, nucleus of insunken epithelium 



All photomicrographs were made on Cramer isochronuitic plates through a ray 

 filter of 2 per cent potassium bichromate, an arc light being the illuminant 

 employed. The lens combination was a Bausch and Tjomb 3^ obj. and a, Zeiss 

 No. 12 compens. oc, the (lamera being so adjusted as to give a magnification of 

 lOOU diameters in each case. The positives were retouched at the microscope. 



EXPLANATION OF FIGURES 



1 lUjdy wall of Planocera inquilina. 



2 Uody wall of I'olychaerus caudatus. 



3 iiody wall of Bdelloura i)r<)pin(iu;i. 



4 Wall of pharynx and i)haryngeal sack of I'lanaria maculata. 



5 Excretory duct of Dendrocoelum lacteum. 



() Sciuiiial vesicle of I^ot liromesost 0111a pcrsoiinf um. 



