ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 71 



describes fully the vegetative characters of the thallus, with special 

 regard to the nuclei ; and he compares these bodies with those of Poly' 

 siphonia and Xemalion, the nuclei of which have been carefully studied. 

 Two methods of cell-division are described ; the nuclei appear to have 

 no part in the process. Branched hairs are frequently borne on the 

 upper borders of the young cells, the function of which is unknown ; 

 they probably perform the functions of absorption and respiration. 

 Sexual and asexual reproduction are very fully discussed, especially with 

 regard to nuclear division, and the behaviour of the tetraspore-mother- 

 cells is compared in tabular form with those of Coralliiui and Polij- 

 siphonia. One poiut is emphasised by this comparison, namely, that at 

 a critical stage in the history of rather closely related members (Poly- 

 siphonia and Griffititsia) of a highly specialised group, the phenomena 

 are of a most varied nature. During the period of synapsis, and up to 

 the time of the formation of the chromosomes, the cytological events in 

 Poly siphon in are more like those in Lilium than those in Oriffithsia or 

 Corallina. From this and other facts, the author concludes that cyto- 

 logical phenomena cannot be considered trustworthy guides to relation- 

 ships. The other points dealt with are tetraspore-like structures on 

 sexual plants, vegetative multiplication, and germination of spores. h\ 

 a final discussion of results the author states that (1) there is in Griffithsi<i 

 an antithetic alternation of generations, the gametophyte being repre- 

 sented by the sexual plants, the sporophyte by the sporogenous cells of 

 the cystocarp ; (2) in addition to this, there is a regular succession of 

 tetrasporic individuals and sexual, individuals. The tetrasporic indi- 

 viduals resemble the sporophyte in number of chromosomes ; they 

 resemble the gametophyte in morphological differentiation. They are 

 to be considered as a phase of an homologous alternation of generations, 

 not the equivalent, wholly or in part, of the sporophyte of Archegoniales. 



Corallinaceae.* — M. Foslie published before his lamented death 

 several papers on this subject. He describes new species of Litho- 

 thamnion, Goniolithon, and Litholepis from various parts of the world, 

 some of which had been previously described as forms by himself in 

 -earlier writings. 



He also makes a new subgenus of Melobesia, which he calls Plio- 

 stroma ; it includes five species, four of which had been previously 

 placed by the author in Lithophyllum, sub-genus Carpolibhon. Plio- 

 -stroma is characterised by having a thallus composed of 5-12 layers of 

 -cells in the part containing the conceptacles, and forms a link between 

 the genera Melobesia and Lithophyllum. 



In another paper, j a continuation of Algological Notes, and consti- 

 tuting the sixth part of the series, a considerable number of diagnoses 

 are published, including species of Lithathamnion, Archseolithothamnion, 

 Goniolithon, Lithophyllum, and Mastophora, some new to science. These 

 are followed by systematic remarks on several genera. Six sub-genera 

 are raised to the rank of genera. Unfortunately the whole paper is 

 in Norwegian. 



In a short note the author describes two fossil calcareous algae 



* Kgl. Norsk. Vidensk. Selsk. Skrift., 1908, Nos 11, 12. 

 t Op. cit., 11)09, Nos. 1, 2. 



