Geology and Mineralogy. 201 



tion to volcanology and is embellished with many beautiful half- 

 tone plates, reproductions of the author's photographs, l. v. p. 



8. Die Jilngeren Gesteine der Ecuatorianischen Ost-Cordil- 

 lere, von F. Tannhaxjsee. Wilhelm Reiss, Ecuador, 1870-1874, 

 Petrograph. Untersuch. II, Lief. II, pp. 119-186, 4°, 1904 Berlin. 

 — This is a continuation of the investigation by Reiss of the 

 rocks collected by him in the Andes ; this investigation has now 

 been carried on for many years in the mineralogical institute of 

 the University of Berlin under the direction of Professor Klein, 

 as noticed in previous issues of this Journal. 



The rocks described are from the Cordillera de Piliaro as far 

 as Sangay, from Azuay and from a part of the Cuenca basin, and 

 comprise the lavas of the great volcanoes of Tunguragua, Altar, 

 Sangay and Azuay. They are nearly all varieties of dacites and 

 andesites whose petrographic characters are given in detail accom- 

 panied by a number of analyses. l. v. p. 



9. Die Alteren Gesteine der Ecuatorianischen Ost-Cordillere, 

 von F. vox Wolff. Ibidem Lief. Ill, pp. 189-304, 1904.— In 

 the work mentioned in the foregoing notice only the geologically 

 receut lavas are considered. The petrographic investigation of 

 the region named above is completed in the present memoir, 

 which gives the results of researches made on the older rocks. 

 These comprise gneisses, amphibole schists, diabases in various 

 stages of dynamic metamorphism, mica schists, granites, gabbros, 

 porphyries of various kinds, etc. These have been carefully 

 studied and correlated and in a number of cases analyzed. These 

 two works add much to our knowledge of Andean rocks and 

 petrology. l. v. p. 



10. Ueber die Chemische Zusammensetzung der Eruptivge- 

 steine in den Gebieten von Predazzo und Monzorii, von J. Rom- 

 berg. Anhang. Abhandl. d. K. Preuss. Ak. Wiss. Jahr, 1904, 

 pp. 135, 4°, Berlin. — In this work the author, in addition to giving 

 a number of new analyses of the rocks of this classic locality, 

 which have been made in connection with his researches by Drs. 

 M. Dittricii and R. Pohl, has assembled all those previously 

 made by other investigators. They are arranged and discussed 

 according to the chemical classification proposed by Osann. The 

 recent work of other geologists in this region is also taken up 

 and critically examined and many dissenting opinions expressed. 

 The new analyses have evidently been well and carefully exe- 

 cuted and add much information to our knowledge of this com- 

 plex and interesting group of igneous rocks. l. v. p. 



11. Septorit, ein-hauyn-monchiquit wts dem Siebengebirge am 

 Rhein, von K. Busz. Xeues Jahrb. f. Min., Bd. II, 1904, pp. 86- 

 92. — This new variety of monchiquite occurs as a narrow dike 

 on the boundary between trachyte and Devonian graywackes and 

 in the hand specimen appears like a fine-grained basalt. The 

 microscope shows it to consist of basaltic augite, a relatively 

 large amount of brown hornblende in fine needles and well crys- 

 tallized violet-blue hauynite. These minerals lie in a colorless 



