EECENT LITEEATURE ON ALGiE. 403 



After some introductory remarks concerning littoral freshwater 

 al2:ae in general, Prof. Giiodat proceeds to the subject of perforating 

 algaB, which he divides into two groups : 1. Perforating algae 

 proper. 2. Carious algae. Of the former group he describes a new 

 genus and species of Chlorophycea, Foreliella perforans. This alga 

 penetrates the living shells of Anodonta anatina var. vycterina 

 Boung., finding its way through the shell to the animal itself. 

 The obvious preference of F. perforans for living rather than dead 

 shells leads Prof. Chodat to indulge in speculations on the possible 

 symbiosis of animal and alga. 



A new species of Gongrosira, G. cocUolifera, is described as 

 growing on chalk-stones, in or near the water. Its rhizoids 

 penetrate the chalk, and from these there arises either a pseudo- 

 parenchymatous mass of cells, or the ordinary filamentous growth. 

 The peculiarity of Gongrosira codiolifera is the production of swollen 

 cells borne on the filaments, which become detached and form 

 propagules. These are figured in various forms and conditions. 

 Unfortunately no diagnosis of the new species is given. 



Growing together with G. codiolifera is found an alga which is 

 considered by Prof. Chodat to belong to Hyella, and he describes it 

 as H.jurana, n. sp. 



The next section of this paper deals with the small furrowed 

 markings on pebbles found on the beach of Jurassic lakes. Various 

 theories have been propounded to account for these markings, but 

 Prof. Chodat agrees with none of them, and attributes the furrows 

 to the action of species of Schizothrix which he finds penetrating 

 the stones. He considers that other Cyanoplujcem follow in the 

 wake of these Schizothrix, but that the actual boring is accom- 

 plished by species of Schizothrix, Plectonema, and Phonnidium. As 

 an explanation of this boring process, he suggests that the algae 

 secrete an acid to dissolve the chalk, but he has found no trace of 

 such acid in portions of the stone attacked by the algae. On the 

 contrary, the reaction has often been alkaline. He is therefore led 

 to form theories on the complicated chemical action of Schizothrix 

 on the chalk, which has marvellous results " selon le temps et les 

 circonstances." He acknowledges however that the origin of these 

 markings is still far from being completely understood. 



The old discussion of alternation of generations in Coleochcete 

 pulvinata is next dealt with, and the systematic position of the 

 genus. Prof. Chodat maintains that Aphanochmte, by reason of its 

 heterogamy, forms a link between C oleo chcete a,nd the Chcetophoraceoi; 

 and he believes that CoUochate forms the end of a series of branched 

 algae which are provided with hairs. He will have nothing to do 

 with the idea that this genus forms the starting-point of the Arche- 

 goniatm ; it belongs to the heterogamous Chcetophora, and the 

 germination of its oospore takes place under special conditions. 

 That is all. He speaks of Prof. Oltmanns' paper, "Die Ent- 

 wickelung der Sexualorgane bei Coleochate pulvinata," in Flora, 1898, 

 pp. 1-14, and points out that this author agrees with him in 

 rejecting the idea of homology between the oogonium of Coleochate 

 and that of Floridece and MiiscinecB, On the other hand, he refuses 



