INTRODUCTION. 3 



Other three orders together, and has come to be 

 regarded as the type of the HepaticcB. 



It is difficult to estimate the number of known 

 species distributed through the world, since the 

 latest *' Synopsis " is now fifty years old. In 1847 

 the total stated by Lindley was seven hundred, but 

 at the present day it cannot be estimated at less 

 than two thousand, and possibly more, of which 

 two hundred have been found in the British Isles. 

 When it is remembered that Dr. Spruce records 

 about five hundred and sixty species for the 

 Amazon and Andes, of which but few are European, 

 it must be conceded that our estimate is the lowest 

 w^hich could be accepted. 



The habitats mostly favoured by the Hepatiae 

 are, for the most part, damp rocks, within the spray 

 of waterfalls or mountain torrents, on damp soil, 

 in bogs, on old trunks, and often intermixed with 

 SpJiagiiiuii and mosses generally. Some are so 

 minute as to be just visible to the naked eye, 

 whilst others attain to several inches, and like the 

 mosses, usually flourish in tufts or effused patches, 

 often of many inches in extent. Whilst the true 

 mosses are for the most part of a bright and lively 

 green, the Jungermannice at least are more seldom 

 of a bright green, but have a wide range of colour 

 from silvery grey, and glaucous, through olive and 

 brown, not uncommonly tinged more or less deeply 

 with purple or rose, and at times nearly black. 



Hepatics do not retain their form or colour so 

 well in drying as do the mosses. The thin leaves 

 shrivel, curl, and collapse, and sometimes become 



B 2 



