Classification of Massive Rocks, 207 
C. [a] Not only by many of the markings already described, but 
especially by more vivid and extensive marks upon the shoulders, 
sides and flanks :—Zebra, wild asses, antelope, giraffe, hunting-dogs, 
ete. 
[b] By special marking of the legs and feet upon the outside :— 
Zebra, antelope, ete. 
D. [a] By most of the lateral and caudal markings already 
mentioned. 
[b] By different colors, according to sex :—Night-hawks and other 
Caprimulgide. 
[c] By difference in extent or shape of markings, according to 
sex :— Antelope, ete. 
E. By various spots and lines, appearing only in the younger 
stages :—Deer, some swine, some Felide, ete. 
SYNOPSIS OF ROSENBUSCH’S NEW SCHEME FOR 
THE CLASSIFICATION OF MASSIVE ROCKS. 
BY W. 5. BAYLEY. 
ACCORDIN G to the new scheme for the classification of massive 
` rocks, proposed by Professor H. Rosenbusch of Heidelberg 
in the. second edition of his “ Mikroskopische Physiographie der 
Massigen Gesteine,” these are divided into three great groups, (I) 
intrusive rocks, (II) vein rocks, and (III) effusive rocks. The 
fundamental notion underlying this classification is briefly as fol- 
lows: the structure possessed by rock masses as we find them in 
the earth is dependent upon two circumstances—(1) the chemical 
composition of their original liquid magmas, and (2) the conditions 
under which these magmas cooled. The effect of chemical compo- 
sition upon the structure assumed by a rock magma in its passage 
to a solid state has not been definitely ascertained. Results recently 
obtained by Lagorio, however, indicate that the composition of — 
the unsolidified portions of rock masses, exerts much more influence 
upon the final structure of the rock than has hitherto been supposed. 
The rapidity with which a rock cooled, as well as the conditions 
under which this took place, have long been known to be quite 
influential in determining its structure. Those rocks which cooled 
