466 WHITMAN CROSS 



is, therefore, not strictly a petrographic system. In the second 

 edition of the Manual (1874), igneous and metamorphic groups 

 were separated in description ; but, probably for the reason that 

 such a course involved the splitting up of granitic, syenitic, and 

 other types supposed to be metamorphic in part and eruptive in 

 part, Dana had, in 1878, evidently adopted the arrangement 

 found even in the last edition of the Manual (1895), whereby 

 crystalline and fragmental were opposed to each other, as by Zirkel 

 in 1866. 



Dana was never able to adopt the modern petrographic sys- 

 tems, founded so largely upon erroneous assumptions, like the 

 age distinction among igneous rocks, or upon genetic views with 

 which he was not in accord, and contented himself with an 

 arrangement of convenience. The main features of this order of 

 description appearing in the Manual of Geology, 1895, are seen 

 from the four primary groups under which all rocks were treated : 



1. Limestones, not crystalline. 



2. Crystalline limestones. 



3. Fragmental rocks, not calcareous. 



4. Crystalline rocks. 



The crystalline rocks were described under five heads : 



I. Siliceous rocks, or those consisting mainly of silica. 



II. Rocks having alkali-bearing minerals as chief constituents. 



III. Saussurite rocks. 



IV. Rocks without feldspar. 



V. Hydrous magnesian and aluminous rocks. 



The second group was divided nearly as in the proposition of 

 1878, above cited. This jesulted in bringing together such 

 unlike things as granite, greisen, minette, slate, agalmatolite, 

 porcelain jasper, obsidian, etc., in the " Potash Feldspar and Mica 

 Series." 



Karl A. Lossen. — Among other protests raised by geologists 

 against the tendency to treat rocks fom the microscopist's 

 alleged narrow standpoint, one of the more philosophical discus- 

 sions had an acknowledged effect making it worthy of notice ; 

 namely, that by Karl A. Lossen, himself a petrographer of dis- 



