ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 281 



Fresh-water Algas from Riga.* — 0. Treboux gives a list of species 

 of fresh-water algee, collected by himself and others in the neighbour- 

 hood of Riga. The Desmids are principally from the marshes near 

 Kuitenhof and Uexkull. 



The Genus Oocystis.f — H. Printz publishes a systematic account of 

 the genus Oocgstis, giving new descriptions of the known species. The 

 inner structure of the cells, the chromatophores, and the pyrenoids, is 

 taken into account. Fourteen species are recognized, while thirteen are 

 regarded as probably good though insufficiently described. Figures of 

 all are given. Some new forms and varieties are described. 



Epiphyllous Algse.J — -N. Thomas publishes some notes on Cephaleuros, 

 a genus of epiphyllous algas. Two forms were received from Ceylon : 

 (1) Large-celled form ; (2) dark-celled form. The structure and mode 

 of growth of these, and of a distinct species from Barbados, are de- 

 scribed. The Ceylon plants have a characteristic mode of growth, and 

 their radial walls have a curious loose posterior end owing to the for- 

 mation of transverse septa, not at the extremity of the radial plate, but 

 at a point slightly farther forward ; and in the first form the disks are 

 associated with fungal hyphaa. The Barbados species is distinguished 

 by its subcuticular habit, and the development of rhizoids, the presence 

 of barren and fertile aerial hairs and subcuticular zoosporangia, and the 

 effect which it produces on the tissues of the host. A resume and a 

 bibliography of previous work on the obscure subject of epiphyllous algse 



are given. 



Stigonema.§ — F. N. Blanchard describes two new species of Stigo- 

 nema — S. anomalum and S. medium — from Essex, Massachusetts. The 

 author compares the characters of these and related forms, and states his 

 view that Hapalosiphon, Sirosiphon, and Fischerella are best regarded as 

 subgenera of SUgonema. The main characters of the three subgenera 

 are set forth in tabular form. 



Spirogyra.|j — E. W. Schmidt describes his experiments on Spirogyra 

 under strong centrifugal force. He finds that the result differs from 

 that of many other plants, inasmuch as the chromatophores which have 

 been thrown about, are reinstated in their normal position apparently by 

 the cytoplasmic filaments. 



Prasiola crispa.^T— F. Brand follows up the history of Kutzimj's genus 

 Schizogonium and its connexion with Prasiola Ag. The views of previous 

 writers are discussed, and the structure of Prasiola crispa is described 

 both in its normal and abnormal forms. Finally the author gives a 



* Korresp. bl. Naturf. Verein Riga, lvi. (1913) pp. 25-7. 

 t Nyt Mag. Natur., li. (1913) pp. 165-203. 

 X Ann. of Bot., xxvii. (1913) pp. 781-92 (1 pi.). 

 § Rhodora, xv. (1913) pp. 192-200 (1 pi.). 

 || Ber. Deutsch. Bot. Gesell., xxxii. (1914) pp. 35-47. 

 i Hedwigia, liv. (1914) pp. 295-310. 



June 17 th, 191 A U 



