Algae. — Fungi, Myxomeceten , Pathologie. 119 



Ostenfeld, C. H. & C. Wesenberg— Lund, A regulär fort- 

 nightly exploration of the plankton ofthe two Icelan- 

 dic Lakes, Thingvallavatn andMyvatn. (Proceedings ofthe 

 Royal Society of Edinburgh. Session 1904—1905 vol. XXV. Part. 

 XII. 1906. p. 1091 — 1167. 2 pls., 1 photograph, figs. in text). 



This is the first record of any systematic investigation of plankton 

 from localities further north than Denmark, and the undertaking was 

 organised by Wesenberg — Lund who reports on the Zooplankton 

 collected, leaving the phytoplankton to Osten feld. The lakes exa- 

 mined were Thingvallavatn in the southwest of I c e 1 a n d , 

 situated in about 64° N. lat., its length being 16 km. and the greatest 

 breadth 8 km. The surface Covers 115 sq. km. the mean depth is 

 35 m. the greatest depth HO m. and it lies 106 m. above sea-level. 

 The other lake, Myvatn, lies in the northern part ofthe Island, 

 about 65° 33' N. lat. and covers an area of 27 sq. km. In this lake 

 no phytoplankton, only Zooplankton, was found. Thingvallavatn 

 cannot be regarded as an Arctic lake for during the entire year in 

 which the samples were taken the surface was not frozen over. Since 

 however the temperature of the water does not rise in summer higher 

 than 11° C. the lake must be regarded as a coldwater one. The 

 phytoplankton consists mainly of a few species of Diatoms, Asterio- 

 neili and Melosirae; Myxophyceae are wanting and both Flagellates and 

 Chlorophyceae are unimportant. The general character is not alpine 

 but rather that of the lakes in the Central European lowland during 

 winter and early spring. It is very poor in species and one of its 

 most remarkable features is the number of organisms one might have 

 expected to find, but which were wanting: for example, Tahellaria 

 fenestratn, Dinohryon sp., Scenedesnms , Pediastruni , Eiidorina , etc. 

 besides all the Myxophyceae. The author gives critical notes on the 

 species which do occur and especially on the Melosirae and Rhiso- 

 soleniae. The chains of Melosirae are curved. Two Rhisosoletiiae are 

 found in samples nearly all the year round. The limnetic Chlorophy- 

 ceae are not abundant, the main form being Sphaerocystis which 

 predominates in alpine lakes and is probably common all over the 

 Central European piain. Ceratiimi hinindinella is quite absent. The 

 authors think it probable that the plankton of the Arctic lakes 

 consists mainly of Zooplankton, to a much greater degree than in 

 more southern countries, and that the phytoplankton, especially in 

 summer time, plays only an insignificant part in those lakes. 

 They believe also that the phytoplankton of arctic and sub-arctic 

 lakes consists in all probability mainly of algae with yellowish or 

 yellowish-brown chromatophores: and that algae with green or blue- 

 green chromatophores are almost entirely wanting. Exceptions from 

 this general rule are Sphaerocystis , the semi-limnetic Desmids and a 

 few rare Chlorophyceae. The paper concludes with remarks on Messrs. 

 West's „Further contribution to the Freshwater plankton ofthe 

 Scottish Lochs," published in the Trans. Roy. Soc. Edin. 1905. p. 477. 

 A list of literature is followed by two plates on which are shewn 

 some of the phytoplankton, and a photograph of Thingvallavatn. 



E. S. Gepp— Barton. 



Clinton, G. P., Ustilaginales. (North American Flora VII. 

 p. 1—82. Oct. 1906). 



This is the first fascicle of this work to appear treating the fungi. 

 In it are treated those fungi which belong to the Ustilaginales in- 



