xxvi INTRODUCTION. 



De Candolle, in their Flore Franpoise and Flora Gallica, and 

 such as has already been adopted in the Monograph of the 

 British JungermannicB. 



Should this Tabula not be clearly understood at first sight, a 

 few remarks will, we hope, render it perfectly intelligible to our 

 readers. The principle consists in presenting, in succession, pairs 

 of opposite characters, between which the student is to choose, by 

 a comparison with the plant, till the required genus be found. 

 Suppose, for example, that he takes Polytrichum as the subject of 

 his investigation. On having recourse to the TABULA GENERUM, 

 he will see, by examining the mouth of the capsule, that it will 

 not accord with the first but with the second character there 

 given, " Peristomio instructo" which carries him to No. 7, where 

 he will again compare his plant with the other character, and will 

 be referred to No. 8. Here he will have no difficulty in discover- 

 ing whether the peristome be single or double, and will conse- 

 quently be carried on to No. 9, where he will, with equal facility, 

 decide upon that character which allows more than four teeth to 

 the peristome ; and on being referred to No. 10, the second line 

 leads his eye to No. 11, where the words " dentibus apicibus con- 

 nexis" are applicable only to the plant in question ; and then pro- 

 ceeding to No. 12, the character against Polytrichum will be 

 found to be the only one that will suit his plant. 



We have referred, with much pleasure, in our first edition, to 

 the valuable " Stirpes Cryptogams Vogeso-Rhenance, auctoribus 

 Mougeot and Nestler ; a work extending to 8 volumes, each of 

 100 species, and consisting of dried specimens of Cryptogamic 

 Plants, which are, unquestionably, of the greatest utility to the 

 Student of these Tribes of Plants. In Germany a somewhat 

 similar publication has appeared, at Baireuth, entirely confined to 

 the Mosses, under the title of " Deutschland Moose ; Ein Taschen 

 Herbarium" &c. or a Moss Pocket-book, by H. C. Funck. In 

 our own country, too, Mr. Hobson of Manchester, and Mr. Drum- 

 ^ 3 



