ZOOLOGY AND BOTANY. MIUUOSCOPV, ETC. 71 



Antarctic Hepaticae.* — B. Kaalaas gives an account of the hepatics 

 gathered on the Crozet Islands by T. Ring and 0. Raknes, in 1907-8. 

 The list includes 15 species, four of which are new to science ; these are 

 figured and described. 



Thallophyta. 



Algae. 



(By Mbs. E. S. Gepp.) 



Algae parasitic on Echinoderms.j— T. Mortensen and K. L. Rosen- 

 vinge describe some plants which are parasitic on Echinoderms. They 

 give la description of Coccomyxa Ophiurae, a Pleurococcaceous alga 

 which attacks Ophioglypha texturata and 0. albida, forming large green 

 patches upon it. The small oblong cells contain a chromatophore with- 

 out any pyrenoid, and sometimes a nucleus, but no starch. The cell- 

 membrane is delicate, and gives an indistinct cellulose-reaction. The algal 

 colonies appear first on the back of the animal, beneath the epidermis, 

 and as they grow, burst off the epidermis, dissolve the calcareous plates, 

 destroy the connective-tissue, and lay bare the intestines, so that the 

 animal dies. Since the Coccomyxa is provided with chromatophores, it 

 cannot be styled a true parasite. On the other hand, Echionophyces 

 mirahilis appears to be a true parasite. It attacks an antarctic Echinid, 

 Rhynchocidaris tripJopora, collected by the ' Gauss ' expedition. It is a 

 problematic organism assuming three forms apparently, and, according: 

 to H. E. Petersen, is intermediate between a Myxomycete and a Phy- 

 comycete, and shows nearest affinity with Pyrrhosorus, an organism 

 which is parasitic on Cystocloniuyn, one of the Floridete. 



Variability of Phytoplankton.J— T. Woloszynska describes the 

 variability of the phytoplankton of the Polish lakes, some forty of which 

 she has examined during the past two years. Some of these have an 

 outlet to the Baltic, but most of them to the Black Sea. Among the 

 species, the variations of which are described and figured, are Ceratkm 

 Mnmdiiiella, Aster ionella gracillima, Diatoma ehmgatum, Attheya Zac- 

 hariasi, RhizosoUnia eriensis and R. longiseta, Steplianodisnis HanUchii, 

 CycloteJla con tea. 



Peridiniopsis and Peridinium.§ — L. Mangin transforms Diplopsah- 

 lenticula Bergh. into two new species, placing its type in Feridinioj)sis 

 and renaming it F. asymetrica, while its form (Diplopsalis Unticida ii 

 minor Paulsen) he places in Peridinium under the new name P. Paid, 

 sent, a synonym of which is P. hntkulatum Mangin (non Faure-Fremiet). 

 The genus Diplopsalis is characterized by the presence of five pre- 

 equatorial plates ; Peridiniopsis has seven. Peridinium has a single 

 antapical plate, while Peridiniopsis has three. These three very homo- 

 geneous genera Mangin proposes to include in one tribe Peridiniefe ; they 



^ * Nyt Mag. Naturvid. Christiania (1911). See also Hedwigia, li. (1911) Beil)!. 

 p. 117. 



t Overs, k. Dansk. Vidensk. Selsk. Forh. (1910) pp. 339-354 (1 pi. and figs.). 



X Bull. Intemat. Acad. Sci. Gracovie (1911) pp. 290-314 (8 figs.). 



§ Comptes Rendus, cliii. (1911) pp. 644-9 (figs.). 



