46 SCIENCE PROGRESS. 



done much to direct attention to the existence of the prob- 

 lematic Girvanella in many British limestones. In his most 

 recent communication x on this subject the author speaks of 

 the discovery of new and interesting forms of this alga (?), 

 and of its share in the composition of the Wenlock lime- 

 stone. Mr. Wethered's paper should be consulted for a 

 fuller account of Girvanella, and for references to other 

 papers treating of this widespread fossil. 2 



Passing on to the Devonian period, we may briefly 

 notice two contributions from Prof. Penhallow on certain 

 plants from Canada. In the first of these 3 he gives brief 

 descriptions and photographic reproductions of a number 

 of plant fragments, which, in themselves of no particular 

 botanical interest, are worthy of record as characteristic 

 fossil plants which may possibly be assigned to the class 

 Alga*. The specimens described are in the form of struc- 

 tureless carbonaceous impressions, and as such are by no 

 means perfect. The author of the paper has followed 

 previous writers in giving expression to a resemblance in 

 form, detected in the fossil species, to the vegetative parts 

 of recent algal genera, by adopting such names as Hahse- 

 rites and Dictyotites ; it would probably be better, certainly 

 much safer, to adopt some less committal genus indicative 

 of algal affinities, and not such names as are based on 

 mere external resemblances of vegetative structures. 



The second contribution 4 deals with the problematical 

 genus Nematophyais ; some figures are given of microscopic 

 sections which clearly demonstrate a much less perfect state 

 of preservation than we are familiar with in previously 

 described specimens of this genus. Penhallow's opinion, 

 that Dawson's genus Celluloxylon^ should be included in 

 Carruthers' Nematophyais, receives confirmatory evidence ; 

 he brings forward proof that in certain cases the structure 



1 Quart. Journ. Geo/. Soc, vol. xlix., 1893, p. 236. 



' 2 Ibid., p. 246. 



:! Proc. U.S. Nat. Museum, vol. xvi., 1S93, p. 105. 



4 Ibid., p. 115. 



5 Quart. Journ. Geo/. Soc, vol. xxxvii., 1S81, p. 302. 



