424 
species appear to be prepotent over those of 
more recent origin. This may be understood 
if we represent the union as AA -+ AB, both 
contributing the same ancestral characters, and 
one the same modern ones as the ancestral. 
A very interesting point brought forward by 
Professor Ewart is, that in some cases reversion 
may lead to a sort of rejuvenescence. For in- 
stance, ‘‘If there are any puppies in a grossly im- 
bred litter that take after a good ancestor several 
generations removed, they invariably prove the 
strongest and best.’’ If there is any truth in 
the idea that in man physical vigor is correlated 
not infrequently with a certain rusticity of 
mind, it may be that the phenomenon is one of 
a similar kind. 
T. D. A. COCKERELL, 
East Las VEGAS, NEW MEXICO. 
Geological Survey of Canada, General Index to 
the Reports of Progress, 1868 to 1884. By D. 
B. Downe, B.A.Sc. Ottawa. 1900. Pp. 
475. 
In the terms of the prefatory note by Dr. G. 
M. Dawson, Director of the Geological Survey, 
‘‘the present General Index begins with the 
volume of 1863 for which an entirely new in- 
dex has been made, and embraces the succeed- 
ing reports to that of 1882-83-84 inclusive. It 
covers sixteen volumes and two short sum- 
maries, making in all 6,585 pages of text to 
which more than 31,000 entries are given. It 
thus provides a ready means of reference to 
practically the entire body of observations pub- 
lished by the Geological Survey up to the year 
1884.”’ 
From 1885 to the present time, ‘ Annual Re- 
ports’ have been issued by the Department, 
each of which is separately indexed. The ‘Gen- 
eral Index’ just issued forms publication No. 
638, of the Geological Survey and contains 475 
pages of text divided into three parts, viz: 
Part 1. Districts described in the several 
reports. 
Part 2. Special Examination. 
Part 3. The General Index. 
These include: (1) The reports analyzed geo- 
graphically and arranged under Provinces, 
Counties and Districts, so that under any 
county or district in a province, a list of refer- 
SCIENCE. 
(N.S. Vou. XIII. No. 324. 
ences to reports, arranged in chronological or- 
der, is given. (2) Ores, rocks, minerals or fossils, 
that have been subjected to assay, analysis, 
microscopical examination, that were scientific- 
ally described. (8) The general index of which 
the following are the principal points: the ar- 
rangement under a reference to a place being 
usually chronological, while under a subject 
references will be found alphabetically ar- 
ranged, or incase of common occurrences, as of 
iron, fossil, etc., localities may be grouped un- 
der provinces. 
The ‘Reports of Progress of the Geological 
Survey of Canada’ and the ‘ Annual Reports’ 
of the same contain a vast amount of useful 
and practical information on the mineral and 
other natural resources of the Dominion, as 
do also the maps which accompany these 
reports, giving in a graphic form the leading 
geological features of the territory included. 
This ‘General Index’ is therefore hailed with 
delight not only by all who are interested in 
the resources of the great Dominion as a work 
which gives ready reference to the various 
economic products in a series of volumes con- 
taining 6,585 pages of text, but also by all 
students in science who may desire to carry on 
further researches in the various districts com- 
prised in the reports treated. The amount of 
time henceforth to be saved in searching for 
information on the thousand and one points 
referred to in each of the volumes indexed 
cannot be over-estimated, and all persons into 
whose hands this index falls will bless its pro- 
jector as well as author. An index to all the 
geological maps referred to in the Reports may 
be found under the word ‘ Maps.’ 
Mr. Dowling’s index will also be of special 
value for bibliographic references, as the work 
performed by various officers of the Geological 
Survey from 1866 to 1885 falls under the name 
of each officer ; and, as the readers of the Ottawa 
Naturalist are aware, in Vol. XIV., No. 6, of 
that Magazine for September, 1900, Mr. Dow- 
ling gave a chronological index to the field 
work done by the officers of the Survey from 
its commencement to 1865, so that there is now 
available for ready reference a complete history 
of geological work done in Canada from 1843, 
the year when the Geological Survey of Can- 
