Mr, Valentine on the existence of Stomata in Mosses. 245 



young state, i. Pedicel of the columella ; — most mosses have 

 the pedicel solid, j. Loose tissue of the apophysis, hk. Stomata 

 opening into the intercellular spaces of the apophysis, through 

 which they communicate with the cavity between the sporular 

 and thecal membranes. I. Opercular membrane, m. Peristome, 

 n. Metula — the opercular membrane of Greville and Arnott. 



Fig. 8. Longitudinal section of a stoma, from a dried specimen of the 

 same. a. The ring cut through. 



Fig. 9. Transverse section of the same. 



Fig. 10. Stomata of a dried specimen of Dissodon splachnoides. 



Fig. 1 1 . Transverse section of a stoma of the same. 



Note. — Fig. 1 and 7 are magnified 35 times ; all the others are magnified 

 100 times. 



VOL. XVIII. 2 K 



