1883. ] Recent Literature. 765 
vey of Canada. The considerations which should guide the final 
selection of a uniform system, must be—first, availability for prac- 
tical use ; and second, the extent to which any given system has 
already been perpetuated in existing cartography. 
e important condition first mentioned obviously includes the 
presentation of a sufficiently large number of sufficiently distinct 
colors or patterns, to include all the minor geological divisions 
which have been, or are to be, discovered. From this standpoint 
the plans sent in by the committees to the Congress of Bologna 
are very defective. Their authors apparentiy forgot that Europe 
constitutes but a small part of the world, and that the system to 
be adopted must represent America, Asia, Africa, and Australia 
The United States system, devised by Powell, is much better in 
this respect. A combination of this with the European scheme 
would do very well for the continents where they originated, but 
we suspect that even this combination would not be sufficient for 
the entire world. A larger list of colors and pattern variations 
even than that offered by Powell, will be required when the geology 
of the world comes to be known. In using them, also, care must 
be observed to allow vacancies for the undiscovered formations, 
In 
bility of a meeting of the British Association for the 
steamers has offered extensive facilities to the visiting members, 
and the hospitalities of Montreal have been freely proffered. A 
large number of members have signified their intention of avail- 
ing themselves of this opportunity of visiting our continent. 
It is desirable that the meeting of the American Association, 
held the same year, shall be fixed at such a time as will enable 
the visitors to attend it also. The locality should not be remote 
from Montreal, and should be of easy access. An invitation will 
probably be sent from Philadelphia, the birth-place of the Amer- 
ican Association. Should this be accepted our British friends may 
expect a warm and appreciative welcome. The Academy of 
Natural Sciences, the American Philosophical Society, and the 
Franklin Institute have appointed committees to take the matter 
in charge. 
Ea S a ATERT 
RECENT LITERATURE. 
Wuire’s Non-MarINE Fossi MoLLUsca oF NORTH AMERICA. 
—In this work the palæontological student has for the first time 
1 Department of the Interior, U. S. Geological Survey. J. W. Powell, Director. 
A review of the non-marine fossil Mollusca of North America, By CHARLES A. 
Waite. Extract from the annual report of the director of the U. S. Geological 
Survey, 1881-82, Washington, 1883. Large 8vo, pp. 144, 32 plates. 
