1026 SUMMARY OF CURRENT RESEARCHES RELATING TO 



clots," " puncta," Sec, of authors are all ono and the same thing under 

 varying microscopical interpretations, idiosyncrasies, or preconceived 

 ideas. 



Schmidt's Atlas der Diatomeenkunde. — Parts 23 and 24 of this 

 work are published, and include eight plates of the genera Auliscus, 

 Aulaeodiscus, Eupodiscw, Pyrgodiscus, Adinoptychus, Triccratium, and 

 Trinacria. 



Alleged Fossil Algae.* — In this memoir M. A. G. Nathorst replies 

 to the objections raised by the Marquis of Saporta and MM. 

 Lebescoute and Delgado, to the opinions previously published by the 

 author, that many of the supposed fossil algae are in reality nothing 

 more than the tracks of animals, or phenomena of purely mechanical 

 origin. Tho fossils whose nature is thus contested are commonly 

 known as Cruziana or Bilobites, Harlania, Eophyton, and some other 

 genera. They generally present themselves in demi-relief on the 

 under surface of the beds in which they occur. No traces of organic 

 substances are found associated with them, and they are composed of 

 the same minerals as the matrix in which they are imbedded. The 

 theory of their vegetable character rests on the peculiarity of their 

 markings, which are supposed to be incapable of being produced by 

 the tracks of organisms. Dr. Nathorst, however, shows that whilst it 

 is difficult to understand how alga? would thus form casts in demi- 

 relief on the under surface of the beds, such structures would be the 

 natural results of the filled up tracks or burrows of marine organisms. 

 Of the manner in which these could be made, the author gives prac- 

 tical proof by passing a movable roller, shaped like a double spindle, 

 over the surface of a layer of soft mud, and then, by means of gypsum, 

 obtaining moulds of the concave impressions. Photographs of these 

 moulds are given in accompanying plates, and they faithfully re- 

 present in almost every detail the supposed algae. The author by 

 no means denies the probable occurrence of true algae in Palaeozoic 

 strata, though he considers that most of the forms described as such 

 by Saporta have no claim to be included in the vegetable kingdom. 



Fungi. 



Fungus-pigments.f — According to Herr E. Bachmann the sub- 

 stances which give the bright colour to fungi are of three kinds, viz. 

 — (1) A product of excretion on the cell-wall or in the intercellular 

 spaces ; in Paxillus atrotomentosus and Agaricus nrmlllatus this pigment 

 is crystalline ; in Lenzites ssepiaria of the nature of a resin. (2) A 

 pigment colouring the cell-wall itself ; of this description are all 

 those which give the brown, red, or red-brown colour to the apothecia 

 of lichens. (3) A constituent of the cell-contents, as in the 

 Uredineae, Tremellini, and many species of Peziza, where an oily sub- 



* Nathorst, A. G., 'Nouv. Observ. sur des Traces d'Animaux et autros 

 Phenomenes d'origine purement mechanique decrits comme " Algues Fossiles,'' ' 

 5 pis. and numerous figs., Stockholm, 1886. See Geol. Mag., 1886, pp. 409-10; 

 also Prof. W. C. Williamson in Nature, xxxiv. (1886) p. 369. 



t Ber. Deutsck. But. Gesell., iv. (1886) pp. 68-72. 



