38 BEITISH MOSSES. 



capsule which produces the spores is, perhaps, the most 

 peculiar and characteristic. If the reader will refer back to 

 Figs. 1 and 2, he will see the capsules (c in Fig. 1, a in 

 Fig. 2) borne on the end of the long stalks (s). The cap- 

 sule, as is shown in Fig. 2,. is covered with a delicate veil 

 or calyptra, which is shown as removed at cal. This veil 

 is the remains of the archegone, borne up by the stalk or 

 seta in its upward growth. In the case of the Polytrichum, 

 it is covered with a thick coating of depending hairs, a cir- 

 cumstance which gives its name to the genus. When the 

 veil is removed, the capsule itself is disclosed (c in Fig. 2), 

 surmounted by an operculum or lid (o), which fits on to the 

 top of the capsule like the lid on a box. The capsule with 

 the lid removed is shown at the letter c'. 



If the reader will refer back to table A, he will find that 

 the Acrocarpous Mosses, i.e., those which produce their 

 capsules at the end of the axis, are divided into Stegocarpae 

 and Cleistocarpae. We are now in a position to appreciate 

 this distinction. In the Cleistocarpous Mosses, the 

 capsule is never differentiated into the two parts of the 

 true capsule and lid ; it remains always as a closed 

 capsule until the walls decay or break, and so emits the 

 spores which it contains. Of this class, the clay Moss or 

 Phascum (Fig. 17) is a familiar example. As a whole, 

 this class is less highly organized than the Stegocarpous 

 Mosses such as the Polytrichum where the capsule, 

 originally a single organ, becomes differentiated into the 

 two parts already described, and the spores are retained in 

 the capsule dry and snug until the ripened lid falls off and 

 allows their escape. 



