INTRODUCTION. XXU1 



I have ventured to revive, in the case of generic names, what 

 was I think a feature of considerable assistance to beginners in 

 some of our older works, viz., the indication of their correct 

 pronunciation, by an accent placed over the vowel of the accented 

 syllable. 



The Key to the Genera and the Keys to the species under 

 each genus have been re-written, to suit the arrangement of the 

 work, by the Rev. H. G. Jameson, from his " Illustrated Guide to 

 British Mosses." They will, I have no doubt, be found of 

 material assistance to the beginner, especially in the larger 

 genera; but it must always be borne in mind that they are 

 intended as a guide to, not as a substitute for, the fuller 

 descriptions. 



The Plates are based upon those published by the Rev. H. G. 

 Jameson in the above-mentioned work ; they have however all 

 been re-drawn and in many cases have been improved and added 

 to, while between 20 and 30 species and sub-species are here 

 figured which were not included there. They have all been 

 drawn direct from nature by means of the camera lucida, and 

 against each figure will be found the scale of magnification used, 

 the sign x 1 being employed for unmagnified figures. The scale 

 has been kept uniform throughout the entire series in the figures 

 of the leaves (x 15), the leaf-apex ( x 60), and the leaf-cells ( x 180), 

 so that the figures show not merely the form, but the comparative 

 size of the structures. The advantages derived from this are too 

 obvious to need pointing out. 



Each species and sub-species described is represented, and 

 the five introductory plates will be found very useful by the 

 beginner, as illustrations of the technical terms used in the body 

 of the work ; references to these will be found in the Glossary. 



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