4 88 SCIENCE PROGRESS. 



(15) FOUQUE, F., and Levy, A. Michel. Min'eralogie Micro- 



grapJiique ; rochcs fruptives francaises. zj-to. Paris, 1 879. [The 

 grouping takes account of geological age, mineralogical 

 constitution, and structure. Under the second head the 

 divisions are based on the dominant felspathic or felspathoid 

 constituent and subdivisions on the chief ferro-magnesian 

 element. Under structure the broad divisions are the 

 granitoid and the trachytoid. Most French writers have 

 followed this arrangement.] 



(16) ROSENBUSCH, H. Ueber das Wesen der kornigen und 



porphyrischen Structur bei Massengesteinen. Neu. JaJirb. 

 fur Min., vol. ii., pp. 1-16, 1882 ; with table. [The structure 

 (even-grained, porphyritic, or glassy) is used as a factor in 

 the classification, in conjunction with the dominant felspathic 

 and ferro-magnesian minerals.. 



(17) Wadsworth, M. E. Lithological Studies. Mem. Mus. Com- 



par. Zuol. Harvard, vol. xi., part i., 1884. [The author's 

 ideal " natural " classification is one " which will place to- 

 gether those forms nearest allied in their general characters, 

 composition, structure, and origin, when the rock as a whole 

 is considered and not certain of its characters only ".] 



(18) BOMBICCI, LUIGI. Considerazioni sopra la classificazione 



adotta per una collezione di litologia generale, con quadri 

 sinottici e catalogo sistematico. Mem. Accad. Sci. Inst. 

 Bologna (ser. 4), vol. v., 1884. 

 BOMBICCI, Luigi. Cor so di litologia. i2mo. Bologna, 1885. 



(19) BONNEV, T. G. Anniversary Address of the President (of the 



Geological Society). Quart. Journ. Geol. Soc, vol. xli. Proc> 

 pp. 57-96, 1885. [The author attaches importance in the first 

 place to chemical (and by implication, mineralogical) composi- 

 tion, and secondly to "the physical condition of a rock, whether 

 hyaline or not, the relation of its constituents and the like". 

 He recognises fifteen principal groups founded on these de- 

 scriptive characters.] 



(20) KALKOWSKY, ERNST. ElementederLithologie. 8vo. Heidel- 



berg, 1886. [Rocks of all kinds are distributed in thirty-nine 

 families, which are merely grouped as " anogene " and " kato- 

 gene ". These divisions correspond approximately to erup- 

 tive and sedimentary, except that the latter is made to 

 include gabbros and peridotites, as well as the crystalline 

 schists and allied rocks.] 



(21) JOHNSTONE, A. On the Evolution and Classification of 



Igneous Rocks. Trans. Geol. Soc. Edin., vol. v., pp. 412-420, 

 1887. 



