26 HANDBOOK OF MOSSES. 



are always some multiple of 4 in number, from 4 to 64, and 

 the number is always constant in the species. This fringe 

 may be either single (fig. 15, 2), or double ; that is, there may 



FIG. 14. i, indehiscent capsule of Phascum cuspidatum. 2, dimidiate calyptra. 



be an outer (fig. 5, 3 b) and an inner row (fig. 5, 3 a) of these 

 tooth-like processes. The teeth of the peristome vary in 

 form and structure; in some cases, as in certain of the 

 Weissias, they are very rudimentary; in others, as in 



FIG. 15. Capsule of Grimmia. i, urn. 2, peristome. 3, conical lid or operculum. 



Funaria, they are elaborately developed, and beautifully 

 marked with transverse and longitudinal striae or markings. 

 The teeth are often simple, but may be cloven, as in 

 Dicranella heteromalla; sometimes straight, as in Didymodon 

 rubellus ; or much twisted, as in Tortula muralis, etc. In 

 the Polytrichums the mouth of the capsule is closed by a 

 beautifully reticulated diaphragm (fig. 16, 3 a), to which the 



