8 TASMANIAN BRYOPHYTA, 



commonly, it is adorned by one or two series of hygroscopic 

 teeth, the peristome. When there are two series, the outer 

 is the exostome, the inner the endostome. 



The seta and capsule have an epidermis, and in some 

 instances possess effective or abortive stomata. 



The classification of mosses has exercised the ingenuity 

 of botanists for many generations. Some few families can 

 be readily sorted out, but the greater number of species are 

 so much constructed on one type, it is next to impossible to 

 arrange them in natural families. Formerly the peristome 

 was largely used as a means of grouping, but it is now con- 

 sidered of too artificial a character, and general habit is 

 more depended upon. The following families are repre- 

 sented in Tasmania, and a fuller description will be found 

 under the proper headings. 



Mosses may be classified into four natural, but very 

 unequal divisions : — ■ 



ARTHRODONTS : so named because the teeth of the 

 peristome are made up of many distinct cells, giv- 

 ing them a jointed appearance. 



ANARTHRODONTS : the peristome teeth are not 

 segmented off by cells, but have usually the char- 

 acter of simple bristles. 



SCHIZOCARPS : without a mouth, the capsule opens 

 by four or eight longitudinal slits. 



SPHAGNA : bog mosses of spongy structure, and a 

 very distinct habit. 



Div. 1, ARTHRODONTEL— The teeth of the peris- 

 tome are transversely jointed ; they are typically sixteen 

 in number ; each tooth may be simple, or may be split more 

 or less deeply into two legs. On the other hand, they may 

 be geminate, that is, united in pairs or bigeminate, that 

 is, united in fours. Sometimes the peristome is reduced or 

 absent ; in a few forms no mouth at all is formed ; in these 

 cases the plant is placed here from the resemblnnce of its 

 other characters. Nearly all mosses met with belong to 

 this division ; they have all the same character of soft deli- 

 cate structure. 



ARTHRODONTS are again divisible into two natural 



