204 



MOSSES AND FERNS 



CHAP. 



form the two rows of membranaceous teeth that surround the 



Fig. roi.—Fimaria hygrometrica (Sibth.)- A, Young ; B, older stoma, from the base of the capsule ; 



C, vertical section, X 360. 



mouth of the urn (Fig. 102). By the drying up of the thin- 

 walled cells between the annulus and the margin of the theca 

 the operculum is loosened and is very easily separated. The 



B. 



Fig. 102. — F-iinaria hygrometrica (Sibth.). A, Part of the peristome ; o, an. outer tooth ; z', one of the 

 inner teeth, X85 ; B, section of the seta, X260 ; C, cross-section of upper part of calyptra, XS25. 



teeth of the peristome are extremely hygroscopic, and probably 



