202 SUMMASy OF CURRENT RESEARCHES RELATING TO 



Diatomiferous Deposits in the Valley of Toxi, Ixtlahuaca, Mexico. 

 — E. D. LozANO {Anal. Inst. Geol. Mexico, 1920, No. 9, 19 pp., 5 pis.). 

 The diatomiferous deposits occur in great abundance among the lacus- 

 trine sediments of the Toxi valley. The first half of this paper is 

 devoted to a geological account of the valley and the sedimentary 

 deposits. The second half deals with the diatoms, which are fully 

 discussed from the point of view of their systematic position and 

 structural details. The paper is in Spanish. • E. S. Gr. 



Cambrian Geology and Palaeontology. IV., No. 5: Middle Cambrian 

 Algse.— C. D. Walcott {Smithsonian Misc. Coll., 1919, 67, 217-60, 

 17 pis.). A study of the algse preserved in the Middle Cambrian 

 Burgess shale of British Columbia. The habitat is described as a 

 deposit from relatively quiet muddy water in a small bay or lagoon in 

 close connexion with the shallow sea. The water was swarming with 

 life. The algse were probably washed into the lagoon by currents and 

 did not grow in situ. Their remains usually occur as shiny black films 

 on the surface of the hard dark siliceous shale. The species described 

 belong to Cyanophycese, ChlorophyceaB (doubtful), and Ehodophycese. 

 The genus attaining the greatest development in species, and abundance 

 of specimens, is Morania, which is referred to Hormogonese, and with 

 some uncertainty to the family Nostocacese. Both macroscopic and 

 microscopic characters are described for this genus. Seven new genera 

 and nineteen new species are described, as well as two new species of the 

 calcareous genus Sphserocodium Rothpletz. They are figured in good 

 photographic plates. E. S. Gr. 



On the Occurrence of Structures like Walcott's Algonkian Algae 

 in the Permian of England. — 0. Holtedahl {Amer.Journ. Sci., 1921, 

 series 5, 1, 195-206). A comparison of the peculiar structures in the 

 Permian magnesian Limestone of the Durham district with those of the 

 Algonkian.Newland Limestone described by Walcott {Smithsonian Misc. 

 Coll., 1914, 64, No. 2). The structures of both types are described, 

 and the author points out that they are identical. He agrees with the 

 opinions of English investigators as to the inorganic nature of these 

 structures, which are regarded as being secondary formations through 

 alterations in the rock. Every transition between the various types is 

 present, and there is no end to the modifications. Some of the characters 

 suggest those developed by crystallization processes. The author does 

 not, however, exclude the possible presence of algse and bacteria in pre- 

 Cambrian strata, as reported by Walcott, since very delicate structures 

 are often preserved in concretions of lime or of silica. E. S. Gr. 



Appendix to Notes on Oceanic Algology. — A. Mazza {Niwva 

 Notarisia, 1921, 32, l-4'8). A continuation, which includes notes on 

 species of RhodophylUs, Erythroclonium, Gelidiopsis, Curdiea, GraciJaria, 

 Hypnea, etc. Gracilaria lichenoides is treated in considerable detail. 



B. S. Gr. 



Remarks on Splachnidium rugosum Grev. — C. Skottsberg 

 {Svensh. Bot. TidsJcnft, 1920, 14, 277-87). A study of the structure 

 and development of this alga found in fresh material collected by the 



