244 Mr. VALENTINE on the existence of Stomata in Mosses. 
existence; and if my pencil will but do justice to my eye and my knife, I - 
feel confident of being able to produce a most interesting analysis. 
_I remain, my dear Sir, yours, very truly, 
Cae Bwld, near Carnarvon, WILLIAM VALENTINE: 
March Ist, 1838. 
EXPLANATION OF TAB. XXI. 
Fig. 1. Longitudinal section of the theca of Orthotrichum diaphanum. 
a. Operculum. 6. Theca. c. Thecal membrane. d. Sporular 
membrane. e. A stoma, the projecting cells of the cuticle being 
open. J. A stoma, the projecting cells of cuticle having closed 
over the stoma. g. Columella. A. Sporular cavity. i. Pedicel 
of the columella. . Apophysis. J. External peristome—the in- 
ternal cannot be seen in section. m. Metula. | 
Fig. 2. External view of a stoma from the same. The projecting cells are 
nearly closed. | 
Fig. 3. The same. The projecting cells are more open, and allow the true 
stoma to be seen within. 
Fig. 4. Internal view of the same. 
Fig. 5. Transverse section of the same. The projecting cells are fully ex- 
panded. 
Fig. 6. Stomata of Funaria hygrometrica—each composed of one cell in the 
form ofa hollow ring. | 
Fig. 7. Longitudinal section of a young theca of the same plant. a. Oper- 
culum. 5. Annulus. c. Theca. d. Thecal membrane. e. Co- 
lumella. f. Sporular membrane. g. Sporular sac. 4. One of 
the strings of elongated cells which connect the sporular mem- 
brane with the thecal membrane ;—these only occur in such 
mosses as have a.space between the two membranes in their 
