ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 307 



Arctic Diatoms.* — H. H. Gran has examined the diatoms collected 

 in the Norwegian North-Polar Expedition of 1893-1896, and classifies 

 them in three groups : — the plankton-diatoms ; those found on the ice- 

 floes ; and the fresh-water forms. Neither the individuals nor the species 

 are so numerous as might have heen expected ; the greater number of 

 the forms found were pelagic. None were found in the intestines of 

 Crustacea (Calanus, &c), which occurred in enormous quantities. It is 

 evident that a number of species live actually on the ice, protected by 

 their gelatinous envelopes. A few new species are described, including 

 one belonging to the genus Xanthiopyxis, hitherto known only in the 

 fossil state. 



Gongrosira.f — W. Schmidle gives a synopsis of the known species 

 of this genus, which he declines to consider, with Hansgirg, as a stage 

 in the cycle of development of Trentepohlia, from its containing a 

 pyrenoid, and other characteristics. Ten species are described, but 

 some of these will probably be suppressed when their life-history i& 

 more fully known. They are arranged in three subgenera: — (1) Eugon- 

 grosira ; sporanges terminal, large, swollen, with many megazoospores ; 

 (2) Ctenocladus (gen. Bzi.) ; sporanges terminal, scarcely distinguish- 

 able from the vegetative cells, swollen or not, containing only a few zoo- 

 spores indistinguishable from those of the vegetative cells ; (3) Meso- 

 sporangium ; sporanges large, produced only in the middle of a filament. 

 The presence of both mega- and microzoospores is not sufficient to 

 entitle Borzi's genus Ctenocladus to an independent existence. 



Coccomyxa g, n.| — Forming a gelatinous mass on moss near Heidel- 

 berg, W. Schmidle finds an alga, apparently identical with Wests' Dactylo- 

 coccus dispar, which he makes the type of a new genus Coccomyxa, 

 with the following diagnosis : — Cells distributed singly, or in twos or 

 fours in a gelatinous layer, longer than broad, with unequally curved 

 sides, rounded or narrowed at the ends, with a parietal chlorophyll- 

 green chromatophore, finely granular protoplasm, and a nucleus ; no 

 pyrenoid; cell-division of the mother-cells oblique, running upwards,, 

 usually simultaneously in two intercrossing directions. The genus 

 probably includes some species hitherto referred to Dactylococcus, and 

 appears to connect Baphidium with Dactylothece. 



Winter-Plankton of Larger and Smaller Lakes.§ — O. Zacharias 

 draws a contrast between the winter-plankton of larger and smaller 

 lakes. In the former the winter is very poor compared to the summer 

 plankton, both in quantity and in the number of forms ; it consists 

 mainly of Copepoda and a few Radiolaria, together with some diatoms, 

 such as Melosira. In smaller lakes, however, the case is very different, 

 and the winter-plankton is comparatively rich and varied. Since the 

 light-conditions are the same in smaller as in larger basins, the author 

 attributes this difference to the mode of nutrition of the floating flora 

 being quite different in larger and in smaller lakes. He believes that 

 many chromophilous algae, including diatoms, have the power of nourish- 



* Scient. Rep. Norwegian North Pole Exped., 1893-6, No. xi. (1900) (3 pis. and 

 chart). See Bot. CentralbL, lxxxv. (1901) p. 194. 



t Ber. Deutsch. Bot. Ges., xix. (1901) pp. 10-S. % Tom. cit, pp. 20-4 (1 pi.). 

 § Ploner Forschungsber., Th. vii. See Bot. CentralbL, lxxxv. (1901) p. 33. 



