THE CLASSIFICATION OF IGNEOUS ROCKS. 489 



(22) ROSENBUSCH, H. Mikroskopische Physiographic der Massigen 



Gesteine, second edition, revised. 8vo. Stuttgart, 1887. 

 [The primary grouping is into " Tiefengesteine," " Gang- 

 gesteine," and " I^rgussgesteine," and these groups are 

 divided into families on mineralogical grounds. The divi- 

 sion into " Aeltere " and "Jiingere," which held a first place 

 in the author's table of 1882, is here abandoned in principle, 

 but retained in practice in the case of the volcanic rocks.] 



(23) Lew, A. MICHEL. Structures ct Classification des Roches Erup- 



tives. 8vo. Paris, 1889. [With strictures on the preceding. 

 The classification arrived at is not essentially different from 

 that given by the author, in conjunction with Fouque, in 



1879.] 



(24) BERTRAND, MARCEL. Sur la distribution geographique des 



roches eruptives en Europe. Bull. Soc. Gcol. Fr. (3), vol. 

 xvi., pp. 573-617, 1888. 



(25) Teall, J. J. Harris. British Petrography: with special re- 



ference to the Igneous Rocks. Royal 8vo. London, 1888. 

 [" The classification is essentially a mineralogical one ; but 

 the rocks are arranged as far as possible according to Bun- 

 sen's law."] 



(26) JUDD, John W. The Natural History of Lavas as Illustrated 



by the Materials ejected from Krakatoa. Geol. Mag., pp. 

 1-11, 1888. 

 JUDD, John W. The Propylites of the Western Isles of Scot- 

 land, and their Relation to the Andesites and Diorites of the 

 District. Quart. Journ. Geol. Soc, vol. xlvi., pp. 341-384, 1890. 



(27) ROSENBUSCH, H. Ueber die chemischen Beziehungen der 



Eruptivgesteine. Tsch. min. u. pctr. Mitth. (N.S.), vol. xi., 

 pp. 144-178, 1889. [Developing the author's "nucleus" 

 (Kern) theory as the basis of a chemical grouping of igneous 

 rocks. 



(28) Roth, J. Die Eintheilung und die chemische Beschaffenheit 



der Eruptivgesteine. Zeits. Deuts. Geol. Ges., vol. xliii., pp. 

 1-42, 1 89 1. [A detailed criticism of the preceding.] 



(29) LOWINSON-LESSING, F. Etude sur la composition chimique 



des roches eruptives. Bull. Soc. Beige. Gcol., vol. iv., 1890. 

 [The author has arrived empirically at formulae expressing 

 relations between silica and bases in igneous rocks, reduced 

 to eight chemical types, and these he finds to correspond 

 with groups defined by mineralogical characters. A table 

 is given.] 



(30) LANG, HEINR. Otto. Ueber die Individuality der Gesteine. 



Tsch. min. u. pet} . Mitth. (N.S.), vol. xi., pp. 467-486, 1890. 



