ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 617 



ture concerning it are cited, but the synonymy is purposely reduced to 

 a minimum. Doubtful species are maintained as species, rather than 

 renamed as varieties ; but their position in the text according to their 

 affinity shows how they can be referred as varieties to typical species. 

 Of the three systematic sections into which the present work is divided, 

 the first — Raphidees (Raphidese) — occupies 233 pages and 50 plates ; the 

 second — Pseudo-raphidees (PseudoraphideEe) — occupies 128 pages and 

 39 plates ; the third — Anaraphidees (Cryptorhaphidese) — occupies 130 

 pages and 50 plates. The pelagic or plankton genera of Diatomaceae— 

 e.g. Chcetoceros — are separated under the name Pleouemees, a special 

 section of Anaraphidees. At the close of their work the authors, in sub- 

 mitting a synoptical table of the genera and subgenera, systematically 

 arranged, discuss briefly the evolution of the diatoms, and adopt the 

 names Centriques and Pennees for the two main divisions of the 

 group. The former name represents the more ancient type, evidently 

 pelagic in origin ; while the Pennees, comprising the Raphidees and 

 Pseudo-raphidees, took their rise from organisms already engaged in 

 vegetal evolution (Chromomonades), whence also sprang the Phaso- 

 phycea?. 



Yorkshire Diatoms.* — R. H. Philip publishes a note on the distri- 

 bution of Diatoma hiemale in East Yorkshire. He discovered quantities 

 of it in AYeedley Springs last summer. He states that it was certainly 

 not present in the springs in 1897 ; and, indeed, it was not found any- 

 where in the East Riding before September 1899. Since then he has 

 gathered it in five localities. But during the last year or two it 

 seems to have increased enormously, and to have ousted almost every 

 other species from Weedley Springs. Figures of three forms of the 

 species are given. 



The same author f found in a sheep-tank above Conistone, in 

 Wharfedale, some rare and interesting diatoms, among them being 

 Amphora Normanii, which was discovered by G. Norman in an orchid- 

 house in 1853, but has not been recorded for Yorkshire since then ; but 

 it has been gathered in Brussels Botanic Garden, and at Cambuslang 

 Bridge, near Glasgow. Gymbeila microcephala and C. leptoceras are new 

 records for the East Riding and for Yorkshire respectively. Figures 

 of these are given. 



Structure of the Diatom-cell.J — 0. Heinzerling treats of the 

 structure of the diatom-cell, with special reference to the assimilatory 

 organs, and the relation of the structure to systematic classification. 

 First he gives an account of the protoplast — cytoplasm, nucleus, 

 centrosome, chromatophores ; then of the assimilatory organs inclosed 

 in the protoplast — double-plates, cell-sap, "volution " (reserve material ), 

 oil-drops, pyrenoids ; also of the cell-membrane and the gelatinous layers, 

 Next he discusses the movements of diatoms, and the characteristics of 

 the structure of the protoblast, and especially of the chromatophores of 

 such genera as have been investigated. He then gives an account of the 



* Naturalist, No. 608 (1907) pp. 312-13 (figs.). 

 t Op. cit., No. 612 (1908) pp. 21-2. 



\ Bibliotheca Botanica, heft 69. Stuttgart : Schweizerbartsche Verlags- 

 buchhandlung (190S) 88 pp. (3 pis.). 



