MINERALS AND GEOLOGY OF CANADA. 425 
sumed to be the case by Retzius, Morton, or any of the earlier inves- 
tigators of national forms of the human skull. To the drachycephalic 
and dolichocephalic types of Retzius, have now been adced the kumbe- 
cephalic, the platycephalic, and the acrocephalic; and to the disturb- 
ing element of designed artificial compression, it is apparent we have 
also to add that of posthumous distortion, as another source of change, 
affecting alike the mature adult, even when old age has solidified the 
calvarium into an osseous chamber from which nearly every suture has 
disappeared, and the immature foetus in which adhesion of the plates 
of the skull has scarcely begun. When more general attention has been 
directed to this element of abnormal cranial development, additional 
illustrative examples will no doubt be observed by craniologists ; and 
the circumstances under which they are found will help to throw 
further light on the peculiar combination of causes tending to produce 
such results. 
A POPULAR EXPOSITION OF THE MINERALS AND 
GEOLOGY OF CANADA. 
(Continued from page 165.) 
BY E. J. CHAPMAN, 
PROFESSOR OF MINERALOGY AND GEOLOGY IN UNIVERSITY COLLEGE, TORONTO. 
on 
PARTE 
ROW ROCKS ARE CLASSIFIED AND DISTINGUISHED: WITH SPECIAL 
REFERENCE TO THE ROCKS OF CANADA. 
In different localities, as a general rule, different kinds of rock 
occur. This must be familiar to the most casual observer. Thus, 
around the Falls of Niagara, and extending for miles across that sec- 
tion of the country, we find vast beds of limestone. About Hamil- 
ton, with other rocks, we have sandstone or freestone. At Toronto, 
our rock-masses consist of beds of clay and gravel, overlying grey 
and greenish shales. Near Collingwood, and again at Whitby, we 
observe dark-brown and highly bituminous shales, containing the im- 
pressions of trilobites in great numbers. At Kingston, we meet with 
limestone rocks differing from those at Niagara, and giving place, as 
we proceed north and east of the city, to beds of crystalline rock of 
