428 SUMMAKY OF CUBRENT RESEARCHES RELATING TO 



on external characters. Characters derived from the siliceous valves are 

 in fact the only ones which can be made use of in prepared specimens ; 

 those derived from the endochrome, the external sheath, or the stipe, 

 being equally fugacious, while the specific characters run into one 

 another in inextricable confusion. M. Peragallo regards the whole 

 family of diatoms as consisting of five groups, which may be clustered 

 round five types, viz.: — (1) Navicula ; (2) Synedra or Nitzschia ; (3) 

 Diatoma or Tabellaria ; (4) Biddulphia ; (5) Coscinodiscus or Melosira. 

 Of these the two first constitute, in general terms, the Placochromaceae, 

 the other three the CoccochromaeeEe of Petit. Also in a general way 

 the first corresponds to the Eaphideae of Smith, the second and third to 

 the Pseudoraphidcce, the third and fourth to the Cryptoraphidete. 



A very large number of species are described, some of them new, 

 arranged in the following sixty genera and twenty families : — 



I. Placocheomace^. Fam. 1, Acbnantheas (^Eaplwneis, Cocconeis, 

 AclinantTies) ; Fam. 2, Gompbonemeae (-Roz'cospAenm) ; Fam. 3,Cymbellea3 

 (Ainphora, Auricula (?) ) ; Fam. 4, Mastogloiace^ (OrtJwneis, Mastogloia) ; 

 Fam. 5, Naviculeae (Navicula, ScJiizonema, Berheleya, Toxonidea, Pleuro- 

 sigma, Donkinia) ; Fam. 6, Amphiproreas (Amphiprora, Plagiotwpis) ; 

 Fam. 7, MtzschieEe (Tryhljionella, Nitzscliia, BaciUaria, Homceocladia, 

 Hantzsciiia') ; Fam. 8, Surirellete (Surirelki, Campylodiseus) ; Fam. 9, 

 Synedre£e {Synedra, Thalassiotlirix). 



II. CoccocHEOiiACE^. Fam. 10, Fragilai-iefe (^Cymatosira, Dimere- 

 grarama, Glypliodesraies, Plagiogrammd) ; Fam. 11, Meridieee (Asterio- 

 nella^; Fam. 12, Licmophoreae (Podocystis, Licmophora, Climseosphenia ; 

 Fam. 13, Tabellarieaa (GrammatopJwra, Bhabdonema, Striatella, 

 Terpsinoe); Fam. 14, Biddulphieai (Biddulphia, Triceratium, Bytilum, 

 lAtJiodesmlum, Hemiaulus) ; Fam. 15, Eupodisceje (Cerataulus, Aidiscus, 

 Aciinocyclus, Euodia) ; Fam. 16, ActinoptychcEe (ActinoptycMs) ; Fam. 

 17, Asterolampreas (Asferolampra, Asteromphalus) ; Fam. 18, Coscino- 

 disceee (^Coscinodiscus, Cyclotella, Eudictya, Stephanopyxis^ ; Fam. 19, 

 Melosirege (Melosira, Podosira, Eyalodiscus, Lauderia) ; Fam. 20, Chfeto- 

 cercce (BJiizosolenia, Cheetoceros, Bacteriastrum). 



Sclimidt's Atlas der Diatomaceenkniide. — The most recently pub- 

 lished parts of this magnificent work, Hefte 27—30, with plates 105-120, 

 relate to the genera Aulacodiscus, Aidiscus, Eupodiscus, Glypliodiscus, 

 Actinoptychiis, Trinacria, Triceratium, Coscinodiscus, Cerataulus, Kittonia, 

 and Biddulpliia. Many new species are described. 



Bacillus muralis and Grotto-ScMzopliyeese.* — Dr. A. Hansgirg 



retmms to this subject, and confutes the view of Tomaschek that the 

 organism known as Bacillus muralis must be a true Schizomycete, be- 

 cause it is altogether destitute of chlorophyll. He reaffirms his state- 

 ment with regard to its genetic connection with ^^^a/io^7iece ccddariorum, 

 and adduces other instances where the presence of a blue-gi'een pigment 

 is not constant in the Cyanophyceae. 



Dr. Hansgirg then enumerates the organisms found by him in dark 

 caves in the limestone mountains of Austria and Bohemia. Among 

 Cyanophycea? he finds Glceothece rupestris, Aplianotliece ccddariorum, and 

 Lynghya calcicola, each presenting a varietal form of Protococcoideae, 

 Protococciis glomeratus, and a Pleurococcus nearly allied to P. miniafus 

 were found. 



* Bot. Cenlralbl., sxsvii. (1889) pp. 33-9. Cf. this Journal, 1888.. p. 786. 



