5 44 The Irish NatioalisL October, 



BRITISH MOSSES. 



The Student's Handbook of British Mosses. By H. N. Dixon, 

 M.A., F.L.S. ; with Illustrations, and Keys to the Genera and 

 Species, by H. G.Jameson, M.A. vSecond edition, revised and 

 enlarged. V. T. Sumfield, Eastbourne, 1904. 18^. 6r/. net. 



It is exactly eight years since this valuable Handbook first appeared, 

 and now we welcome the issue of a new edition. It might have been 

 thought too short an interval, and that there would be some grumbling 

 at having to purchase a new book so soon ; but its appearance is amply 

 justified by the result. Some 600 species and sub-species of Mosses 

 were described in the first edition in 1896. Since then so much activity 

 has been shown in the collection and study of imperfectly-known plants 

 that 30 more have been added in the present one. These are described 

 and figured. Besides this, the whole work has been revised, and much 

 important matter added to the interesting notes on species. There are 

 60 additional pages, and 6 new plates of illustrations. While the former 

 work will not lose its value for beginners, we advise those who wish to 

 become acquainted with the less known species to purchase the new 

 edition. 



Mr. Dixon's book is so well known that it is not necessary to say much 

 about its general features. There is a short, well-illustrated Introduction 

 and glossary of terms. The ke5'S to the genera and species, and 

 Plates 1-60, are from the Rev. H. G. Jameson's " Illustrated Guide to 

 British Mosses." 



The illustrations are truthful, and exhibit such parts as are needful 

 for discriminating species, especially when the plants are without fruit. 

 The only drawback is that there is no life-size drawing of the plant, or 

 means of forming an idea of its habit of growth. F'or this a more 

 elaborate work must be consulted. The additional plates are not so 

 clear or well drawn as the former ones. 



There are keys to the species and full descriptions, salient points con- 

 venient for separating neighbouring species being printed in italics. 

 These are followed by notes on the species in smaller type, which are of 

 great interest. 



The changes in the new edition are chiefly by way of addition. Mr. 

 Dixon's treatment of his subject is, on the whole, conservative, and new 

 species or varieties have not been hastily multiplied. We notice a 

 tendency to group those together which are closely related, and extend 

 the use of sub-species so as to form ultimately what have been called 

 aggregate species, such as Grimmia apocarpa. It may be more difficult 

 to use than a regular lineal series, but we gain a better knowledge of the 

 plants from its use. Dichodontium flavescens, Pottia asperula, and others 

 have been reduced to the rank of sub-species. 



