A VERY readable text on British fresh-water algae by G. S. WEST6 has appeared and will be welcomed as the only work of its kind in English that is up to date. The descriptive portions of the book are clear and the figures excellent. The accounts of the desmids, diatoms, and unicellular green algae deserve special mention. The general arrangement of the groups is quite simple and consistent from the author's point of view, but few specialists would be likely to agree with him, so varied are the

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... lassifications of the algae. WEST'S arrangement is in the main conservative, and the synopses and keys are so clear that the reader cannot be confused. There is a preliminary account of methods of reproduction, sexual organs, polymorphism, and phylogeny. These topics might well have been expanded, as in their condensed form a reader with little knowledge of morphology is scarcely likely to grasp the underlying homologies and evolutionary principles illustrated in the algae. Much more pretentious is a large volume of OLTMANNS7 which is announced as the special part and is to be followed shortly by a second that will treat of general problems. OLTMANNS covers the entire group of the algae, fresh water and marine, excepting the Cyanophyceae, and aims to collect all important literature of recent years. His classification is elaborate, and the arrangement of the great groups is quite different from that in Die natiirlichen. Pflanzenjamilien. However, the families are easily understood, and it is around them that the descriptive matter is collected in convenient form. Reproductive processes are discussed in great detail, especially for the Phaeophyceae and Rhodophyceae, where the advance in our knowledge has been greatest in recent years. The account of the Rhodophyceae, following his interpretation of the cystocarp as involving a sporophytic generation associated with the gametophyte, is an especially valuable contribution, bringing order into what has been one of the most chaotic subjects in botany. The work is very full of figures, some 470, excellently reproduced, many of them covering the greater part of the page. This first volume is sure to find a hearty reception and the second one will be awaited with keen interest.-B. M. DAvIS. Index Bryologicus. THE Index Bryologicus of General PARIS8 was completed in i894 and a supplement was published in i900. It was welcome as a real boon to bryologists and the immense toil of its author was gratefully appreciated. Now it has been 6 WEST, G. S., A treatise on the British freshwater algae. 8vo. pp. 372. figs. i66. Cambridge University Press. I904. ios. 6d. 7 OLTMANNS, F., Morphologie und Biologie der Algen. Vol. I. 8vo. pp. 733. figs. 467. Tena: Gustav Fischer. I904. M 20. 8 PARIS, E. G., Index Bryologicus sive enumeratio muscorum ad diem ultimam anni i900 cognitorum, adjunctis synonymia distributioneque geographica locupletissimis. fasc. II. 8vo. pp. 65-I28. Paris: Librairie Scientifique A. Hermann. I903 2.50 Jr.