128 ANNALS OF SCOTTISH NATURAL HISTORY 



by the consideration of the classification of the sub-class, and its 

 division into orders, families, and genera ; accompanied by diagnoses. 

 Finally, we have the main or systematic portion of the volume 

 treating on the various British species, and giving for each its full 

 synonymy (the preparation of which is the work of Mr. Hopkinson), 

 description, distribution, etc. Every species is figured, there being 

 a series of 16 excellent plates, mostly coloured, from drawings by 

 Mr. Cash. The Ray Society is to be congratulated on having 

 secured Mr. Cash's services for such a desirable work, and its 

 authors on the thorough manner in which they have accomplished it. 



BRITISH DESMIDIACE/E, VOL. II. By W. West, F.L.S., and G. 

 S. West, M.A., F.L.S., being one of the volumes issued for the year 

 1905, to members of the Ray Society. 



This monograph is worthy to rank with the many admirable 

 contributions to Botany and Zoology that have been issued by the 

 Ray Society, and worthy also of the high reputation of its authors as 

 experts in the study of the Freshwater Algae in the British Islands. 

 The first volume was issued in 1904, and there will be others to follow. 



Texts and plates are alike in the care expended on them and in 

 their accuracy. The second volume includes the genera Euastrum 

 (46 species), Micrasterias (19), and Cosmarium (50), and varieties 

 appear under many of the species. For each species or variety, 

 after the name and reference to the plate on which it is figured, 

 there follow an excellent bibliography and synonymy, a full descrip- 

 tion, a statement of the distribution in our islands and abroad, and 

 frequent critical notes. For each genus a key is supplied to aid in 

 identification of the species. No better or more useful monograph 

 of these very interesting plants could be desired. 



THE ALIEN FLORA OF BRITAIN. By Stephen Troyte Dunn, 

 B.A., F.L.S., Superintendent, Botanical and Afforestation Depart- 

 ment, Hongkong. (West, Newman and Co., 54 Hatton Garden, 

 London, 1905.) 



For three or four years before going to Hongkong, Mr. Dunn 

 had devoted his spare time, while residing in Kew and employed in 

 the Royal Herbarium, to accumulating information about the occur- 

 rence of alien plants in Britain, To render that information useful 

 to others he has arranged the plants to which it refers under their 

 families, these following the order of succession familiar in English 

 works. The arrangement within each family is alphabetical. The 

 interruption to the collection of materials caused by the departure 

 from England, and the conditions under which the materials had to 

 be prepared for publication, away from the means of verifying 

 doubtful points, or of filling in gaps, have necessarily interfered 

 seriously with the completeness of the book ; but it contains much of 

 great interest, and forms a store of helpful information. Mrs. Dunn de- 

 serves thanks for her share in rendering that store accessible to others. 



