BRITISH MOSSES. 



39 



In some cases, the orifice of the capsule 

 is formed by a smooth edge or lip ; but 

 in other cases this orifice is surrounded 

 by a girdle of teeth of varying number, 

 form, and colour, so that the study of 

 the peristome, as this girdle is called, 

 presents a continued variation of objects 

 of beauty and interest. Fig. 22 exhibits 

 the peristome of the beautiful little Moss ^ IQ 22. 



the Tetr aphis pellucida, to which I have Peristome of 



, , . , ,, . , ,, , Tetraphis pel- 



already referred. No simpler form of i uc ida, after 



peristome can be found than this, ex- Schimper. 

 hibiting four teeth in a single ring. 

 Fig. 23 is part of the peristome of the Fissidens adiantioides 

 magnified, and shows two phenomena common in 



I'lO. 23. Part of peristome of 

 Fissidens adiantioides, mag- 

 nified. After Schimper. 



. 24. Peristome of Tortula 

 ruralis, magnified. After 

 Schimper. 



