676 SUMMARY OF CURRENT RESEARCHES RELATING TO 



pond at Marburg. These cells measured 25-45 /i in diameter. Associated 

 with this species was Synedra acus Grun. 



Diatoms of Lake Cotronia.* — Matteo Lanzi finds that the species 

 most abundantly represented belong to Cyclotella ; then follow Cocconeis 

 and Synedra, Colletonema and Cymbella. More rarely are found species 

 of Navicula, Pleurosigma, Surirella, and Cymatopleura, Achnanthes lanceo- 

 lata, Campylodiscus, and Odontidium. 



Phyto - plankton of the Erlaufsee, and the Caspian Sea. t — 

 V. Brehm and E. Lederbaner record Anabvena flos aquas Breb., Ceratium 

 hirundinella Mull., Asterionella formosa var. gracillima Grun., Tabellaria 

 fenestrata var. intermedia Grun., and JBotryococcus Braunii Kiitz. The 

 pbyto-plankton of this lake is much more rarely to be found than the 

 zoo-plankton, and there is no one form which occurs sufficiently often in 

 the nets as to be in any way characteristic. The least rare form is Cera- 

 tium hirundinella, which is not found below 5 m. 



C. H. Ostenfeld J gives the result of his examination of plankton 

 collected in the Caspian Sea by the Danish Expedition to Central Asia. 

 The three samples taken showed that a similarity exists between the 

 phyto-plankton of the Caspian ad that of the Baltic, but that endemic 

 species constitute the larger part. The following new species and 

 varieties are described : — Amphorella borealis var. caspica, Diplopsalis 

 caspica, Gonyaulax Clevei, Exuviella cordata, Chsetoceras caspicum, G. 

 delicatulum, C. Paulsenii, C. rigidum, C. simplex, Anabeena caspica, 

 Oocystis socialis. 



Diatoms of the River Olona. § — Benedetto Corti publishes a list 

 of the diatoms found by him in this Italian river. Some years ago he 

 published a paper ' On the Terraces of the Olona,' and the subject made 

 nim desirous of studying the fossil diatoms of the terraces. His re- 

 searches among certain strata were without any but a negative result. 

 He was then led to examine those still living in the river, and found 58 

 different species, of which he gives a list. In the glacial peat of the 

 Olona he had found 18 species, and of these only three are found among 

 the species still living in the river — Gocconeis helvetica Brum, Gompho- 

 nerna acuminatum Ehr., and Cymbella lanceolata Ehr. The marked 

 difference of species between the fossil and the living diatoms of the 

 same region is, in the author's opinion, of importance for the micro- 

 palasontologist. 



Diatoms in Agar-Agar. || — E. Senft gives a short list of the diatoms 

 most commonly found in agar-agar, after the substance has been calcined 

 and reduced to a white ash and then treated with hydrochloric acid. 

 Four species of Grammatophora, Arachnoidiscus ornatus Ehr., species of 

 Cocconeis, especially C. scutellum and its variety parva, and Campyloneis 

 Grevillei Grun. are the species which the author regards as charac- 

 teristic. 



* Atti Pont. Accad. Rom. d. Nuov. Line, lv. (1902) pp. 145-7. 



t Verh. k. k. zool.-bot. Gesell. Wien, lii. (1902) pp. 388-402. 



X Vedensk. Moid. Naturhist. Foren. Copenhagen, 1901 . pp. 1 29-39 (10 figs, in test) 



§ Rendiconti Real. 1st. Lomb., xxxiv. (1901) pp. 764-7. 



|| Zeitschr. f. angew. Mikr., viii. (1902) pp. 85-8 (9 figs, in text). 



