350 SUMMARY OF CURRENT RESEARCHES RELATING TO 



60, 80, and 100 m. Then the actual mass of organisms is less until the 

 " shade-flora " begins, composed of Planktoniella, Valdiviella, Goscino- 

 discus, Antelmindlia, and Halosphmra, which forms a fairly dense vegeta- 

 tion to about 150 m., occasionally even to 200 m. From thence down- 

 wards to 400 m. there is a gradual decrease of cells, and below that 

 depth there are only colourless cells of Peridiiiiinn, Phalacroma, and 

 Diplopsalis. In the lowest depths is found only the rain of dead cells 

 falling to the bottom from the upper strata. The author compares the 

 Indian Ocean phytoplankton with that of the Atlantic, and finds that 

 the warmer regions are characterised by numerous species of diatoms 

 and Peridinere, which are, however, represented by few individuals. As 

 regards vertical distribution of species and quantity, it is the same as 

 that of the Indian Ocean. Special chapters are devoted to neritic and 

 oceanic phytoplankton ; ocean currents and phytoplankton ; quantitative 

 distribution, and its dependence on external factors ; occurrence of 

 vertical currents and their influence ; the different nutritive matters, etc. 

 Other important questions, such as the microspores, the systematic inter- 

 relation of centric and pennate diatoms, the phylogeny of Rhizosolenia, 

 etc., are discussed. 



Beguinot, A., & L. Fobmiggini — Ricerche ed osservazioni sopra aloune entita 

 vicarianti nelle Characee della Flora Italiana. (Researches and observations 

 on certain vicarious entities in the Characese of the Italian flora.] 



Bull. Soc. Bot. Ital., 1907, pp. 100-16. 



Hernandez-Pachecho, E. — Consideraciones respecto a la organizacion, genero 

 de vida y manera de fosilizarse algunos organismos dudosos de la epoca silurica 

 y estudio de las especies de algas y huellas de gusanos arenicolas del sihirico 

 inferior de Alcuescar (Caceres). (Considerations respecting the organisation, 

 mode of life, and manner of fossilisation of some doubtful organisms of the 

 Silurian period, and a study of the species of algse and casts of arenicolous 

 worms of the Lower Silurian of Alcuescar in the province of Caceres.] 



Bol. R. Soc. Espafiola Hist. Nat., viii. (1908) pp. 75-91 (4 pis.). 



Mazza, A.— Saggio di Algologia oceanica. (A study of oceanic algology.) 



[A continuation.] Nuov. Notar., xix. (1908) pp. 1-24. 



Fungi. 



(By A. Lorbain Smith, F.L.S.) 



New Species of Achlya.* — J. D. Pemberton describes this new 

 fungus, which was found in a culture of Saprolegnia, etc., taken from a 

 small brook. It is characterised by the presence of antheridia, which 

 arise immediately below the oogonium ; the fertilising tube rises from 

 the septa that divides the oogonium from the antheridium. Cultures 

 of the new species were made on small gnats in hanging drops, and the 

 whole development was followed with ease. 



Hydnocystis Thwaitesii.f — T. Petch has collected a number of 

 specimens of this rare fungus, and gives a revised and full account of it. 

 The species looks somewhat like a Peziza, and grows on decaying wood. 

 It is a Peziza without a disk : there is a thick wall only, of a cup-like 



* Bot. Gazette, slv. (1908) pp. 194-6 (6 figs.), 

 f Ann. Mycol., v. (1907) p. 473-5 (1 fig.). 



