70 MOSSES AND LIVEEWORTS 



Pellucid Four-tooth Moss (Tetraphis pellucida), as 

 it is called, in consequence of the special form of 

 its peristome, is often common enough, growing 

 on rotting wood, or on peaty ground, it seldom 

 fruits with us. Plate V. fig. 7 is a drawing of 

 the peristome of this moss, taken from a plant 

 that I gathered many years ago in the Alps ; 

 while at fig. 8 of Plate IV.b is one of the 

 capsules of the second of the two species just 

 alluded to, which again shows the four peristome 

 teeth. Most mosses have either eight, sixteen, 

 thirty-two, or sixty-four peristome teeth ; but 

 whatever the number may be, it is invariably the 

 same in all the capsules of any one species, and 

 this feature in moss-structure will, in consequence, 

 often prove a valuable guide to the identity of 

 some particular moss. One could not well have a 

 more striking instance of the wonderful order and 

 exactness of Nature's methods than this fact, that 

 the number, aye, and generally too the colours and 

 markings of these wonderful teeth details most 

 of which, be it remembered, cannot even be seen 

 except when a lens of high magnifying power 

 is used remain constant in any one species of 

 moss, wherever on the face of the globe it may 

 be found. 



Illustrations of this very interesting point are 

 given in figs. 6 and 8 of Plate V.a, where I 

 have drawn a few teeth taken from two members 

 of the great Thread-moss (Bryum) family. These 



