PETROLOGY. 217 



apatite, and small particles of quartz. The uralite is of somewhat 

 different appearance from that of some foreign localities also examined, 

 (Ural, Dolgelly and Tyn-y-groes in Wales, and Viezena at Predazzo in 

 Tirol). He regards the uralite as altered augite, with the crystalline 

 form unchanged. Chlorite or viridite has afterwards replaced the 

 hornblende, the alteration always beginning at the surface of the 

 crystals, and slowly spreading inwards. E. E. 



Terglav, Joh. Die petrographische BeschafFenheit der im Grazer 

 Devon vorkommenden Tuffe. [The TiifFs in the Devonian Rocks 

 of Gratz.] Min. Mitth. Heft iv. pp. 207-228. 

 Describes these rocks with special reference to the microscopic struc- 

 ture of the matrix and of tlie enclosed black and brown fragments. 

 All the tuffs are not related to one kind of rock: some represent 

 eruptions of melaphyro ; others corresj[X)nd with porphyries. Crystals 

 of felspar have been developed in the matrix of some. E. W. R. 



Tornebolim, A. E. Mikroskopiska vergartsstudier. Nos. v.-viii. [Mi- 

 croscopical Rock-studies.] Geol. Foren. StocMohn Fork. Bd. iii. 

 pp. 184-187, 210-218. 



Y. On the distribution of zircon in rocks. — Microscopical zircons are 

 very common in granite, gneiss, porphyry, " eurite," and " hiilleflinta " 

 from several localities in Sweden ; they also occur in some granites 

 from Christiania in Norway, from Robschiitz and Wechselburg in 

 8axony, from Brixen in Tyrol, the so-called Adamello granite, from St. 

 Gotlhard (protogine-granite), from N. America, &c. 



YI. On tourmaline as an accessory constituent of "halleflinta " and 

 *' eurite." 



YII. On calc- granite. — Gives a sketch of the microscopical structure 

 and composition of the rock ; calc-spar (not of secondary origin) takes 

 the place of the quartz. 



YIII. Contribution to the knowledge of the mode of origin of the 

 quartzites. Thinks that at least some of the quartzites are quartz- 

 sandstones, whose clastic structure has been totally effaced by silica- 

 cementation, and replaced by a crystalline structure. E. E. 



[Yarieties of Diabase and Gabbro in Sweden.] Academy of 



Science, Stock-holm, April. [Nature, vol. xiv. p. 174.] 



Umlauft, — . Beitriige zur Kenntniss der Thonschiefer. [Clay 



Slate.] Lotos. 



Wallace, W. Tripolite. Chem, News, vol. xxxiv. no. 878, p. 133. 

 Note on a diatomaceous deposit in Loch Oich, one of the chain of 

 lakes forming the Caledonian Canal. 



Wichmann, Arthur. Ueber Puddingstein. [Pudding-stono.] N. 



Jahrh. Heft ix. pp. 907-918. 

 Discusses the origin of the concentric coloured rings in the fliut- 

 pebbles of the Hertfordshire conglome/ate ; describes the characters 



