356 WHITMAN CROSS 
ments of which these bodies were found capable. Certain geolo- 
gists, as, for instance, De la Beche in England, had, at an early 
day, very clear and logical ideas as to the principles which 
must control classification. In the third edition of his Geological 
Manual, issued in 1833, is the sentence: ‘‘Classifications of rocks 
should be convenient, suited to the state of science, and as free 
as possible from a leading theory.” In accordance with this 
principle, De la Beche divided all rocks (including formations ) 
into stratified and unstratified, ‘independent of the theoretical 
opinions that may be connected with either of these great 
classes of rocks.” The stratified rocks were then subdivided 
into “superior or fossiliferous”’ and “inferior or non-fossiliferous.” 
By this logical division De la Beche at once secured classes or 
subclasses corresponding well to those now called igneous, 
metamorphic, and sedimentary. 
Carl Friedrich Naumann, 1550, 1855.—Without attempting a 
complete history of the introduction of each factor into classifi- 
cation, we will now consider the system of Carl Friedrich Nau- 
mann, the great Saxon geologist, as of much importance in 
presenting a new mode of treatment. The first edition of his 
Lehrbuch der Geognoste appeared in 1850, the second in 1858. 
Naumann was a great systematist; he viewed rocks from many 
standpoints, and from each constructed a peculiar scheme of 
treatment. Thus one section of the Geognosie was called ‘‘ Petro- 
graphie oder Gesteinslehre,” defined farther as a branch of 
“Chthonographie oder die Geognosie im engeren Sinne des 
Worts.” This is the first use of petrography of which I have 
knowledge. It is used in the sense of petrology, as the latter 
term is now commonly applied in America. 
Naumann not only gave the comprehensive science of rocks 
a special name, but he established within it six divisions, 
namely: 
A. Hylology, a discussion of the constituents of rocks. 
B&B. Histology, on texture and structure of rocks. 
