204 THE JOURNAL OP BOTANY 



unpleasing appearance. Mr. Salmon has condensed into small 

 space a great amount of information as to dates, localities, &c., 

 and in this sets an example of conciseness which might well be 

 followed by future writers, and contrasts favourably with that 

 of some who have preceded him in these County Histories. A 

 " complete list" follows these district enumerations. 



A Monograph of the British Desmidiacece. By W. & G. S. West. 

 Vol. iv. Eay Society, London, 1912. Pp. xiv and 191 ; 

 plates 96-128. 



All algologists will welcome the appearance of the fourth 

 volume of this highly useful work. An interval of nearly four 

 years has passed since the publication of the third volume, and it 

 is to be hoped that the two remaining volumes will appear in 

 more rapid succession. The number of species of Desmids has 

 become so considerable and their descriptions are so scattered 

 that a careful monograph such as this has become a matter of 

 urgent necessity. Now that the genus Cosmarium, with its two 

 hundred and fifty-one species and numerous varieties, is completed, 

 the authors may be congratulated on the successful accomplish- 

 ment of a very difficult task. It is necessary to attempt the deter- 

 mination of a species of this genus with other available sources to 

 realize the debt that we owe to the authors. 



Apart from the completion of the genus Cosmarium, the volume 

 deals with the genera Xanthidium and Arthrodesmus , and with 

 the first forty-one species of Staurastrum. The great diversity of 

 the species of the last-named genus renders a classification par- 

 ticularly difficult. Messrs. West do not accept Lundell's sub- 

 genus Pleur enter ium, since the character on which it is based 

 {viz. parietal placing of the chloroplasts) is doubtful, and has the 

 effect of bringing together a number of species which appear to 

 have no other relationship with one another. The authors dis- 

 tinguish two divisions, depending on the absence or presence of 

 processes at the angles of the semicells ; the species are further 

 classified into ten sections, based on the shape of the cell and the 

 character of the membrane. This system serves to classify the 

 bulk of the species, but there are a number of intermediate forms 

 of which the exact systematic position is somewhat doubtful. As 

 in the case of Cosmaritim, we are probably dealing with a genus 

 in active process of evolution in which the numerous intermediate 

 types render an ideal classification impossible. 



A number of new varieties and three new species {Xanthidium 

 Orcadense, sp. n., Staurastrum pilosellum, sp. n., and S. inflatum, 

 sp. n.) are described in the present volume. 



F. E. F. 



Practical Botany. By F. Cavers, D.Sc, F.L.S. W. B. Clive. 

 Pp. xvi, 408, with 92 text-figures. Price 4s. ^d. 

 We do not remember any book of its class and size that attempts 

 quite as much — and accomphshes much — as does this little volume 



