102 SUMMARY or CURRENT RESEARCHES RELATING TO 



contained JV". Durrandii, not so fine as those occurring in tlie gathering 

 from the island of Rea ; many of the valves are buUate on each side 

 of the median line ; the presence or absence of these markings is, 

 however, of no specific value. 



Diatoms of Hot Springs.* — Count F. Castracane enumerates the 

 diatoms found among the " muffe " in the hot springs of Valdieri, at a 

 height of 1336 metres, the temperature of the water varying between 

 28° and 69° C. in different springs. He finds the prevalent forms not 

 to be those usually found at high elevations, from which he draws the 

 conclusion that the distribution of diatoms is dependent rather on 

 temperature than on altitude. 



Composition of the Marine Tripolis of the Valley of Metaurus.f — 

 According to Count F. Castracane, the community of types of 

 diatoms in all the marine tripolis of Italy indicates that they are a 

 portion of one and the same deposit. In the tripolis examined by him 

 from the valley of the Metaurus between Fano and Fossombrone, the 

 diatoms are nearly all of familiar species. But the following new 

 genera are described : — Thalassiotrix. — Frustulis linearibus radiatis per 

 pulvillum gelineum armilliforme unitis, bino erectiorum punctulorum 

 ordine instructis ; post frustulorum deduplicatione armilla disrumpitur, 

 et frustula in seriem alternam per isthmum triangularem coalescunt. 

 Etmodiscus. — Frustula solitaria discoidalia ; valvis tenuissime et in- 

 conspicue striolatis; forma plus minus convexa, quandoque diversi- 

 mode denticulata ; zona connectiva punctulata. 



Classification of the Cyanophycese.^ — Dr. A. Hansgirg gives a 

 synopsis of all the known genera and subgenera of Cyanophycese, or, as 

 he prefers to call them, Myxophyceje. He arranges them under three 

 orders, viz. : — (1) Glceosiphb^ (suborders HeterocysteaB and Iso- 

 cystese) ; genera, Stigonema, Eapaloaiphon, Mastigocoleus, Capsosira, Nosto- 

 chopsis, Scytonema, Tolypothrix, Plectonema, Desmonema, Hydrocoryne, 

 Diplocaulon, IsacHs, B,ivularia, Gloeotrichia, Brachytrichia, Calothrix, 

 Sacconema, LeptocJisete, AmpMthrix, MicrocJisete, Nostoc, Anahsena, Nodu- 

 laria, Microcoleus, Inactis, Symploca, Lynghya, Isocystis, Aphanizomenon, 

 arranged under various subfamilies and tribes. (2) Chamjesiphonace^ ; 

 genera, Chamsesiphon, Clastidium, GodlewsMa, Hyella, Cyanocystis, 

 Dermocarpa, Cyanoderma, Pleurocapsa. (3) Cheoococcoide^ ; genera, 

 Allogonium, Oncobyrsa, Xenococcus, Entophysalis, Homalococcus, Placoma, 

 Gloeochsete, Chroothece, Gloeothece, Aphanothece, SynecJiococcus, Dactylo- 

 coccopsis, Glaucocystis, Coccochloris, Merismopedium, Tetrapedia, Coelo- 

 sphserium, Gomphosphseria, Clathrocystis, Polycystis, Gloeocapsa, Aphano- 

 capsa, Chroococcus, Cryptoglena, Chroomonas. Oscillaria is reduced to a 

 subgenus of Lynghya. 



Dactylococcopsis is a new genus, with the following characters : — 

 Cellulae graciles, solitari«e vel 2-8 in familias fasciculatim consociatse, 

 fusiformes, subovatae-lanceolatse, modice vel falcato-curvatse, utroque 

 polls angustatis, subacutis vel longe cuspidatis. Cytioplasma pallide 

 serugineum vel olivaceo subcseruleum, granula oleose nitentia, bina raro 

 pluria vel singula includens. Membrana tenuis, homogenea, lasvis. 

 Propagatio fit cellularum divisione ad unam directionem. The only 

 species, D. rhapMdioides, was found on wet rocks. 



* Notarisia, iii. (1888) pp. 384-6. Cf. this Journal, 1888, p. 633. 



t Boll. Soc. Geol. Ital., v. (1886) 7 pp. $ Notarisia, iii. (18SS) pp. 584-90. 



