| that certain Brachiopods have been but slightly modified from an extremely remote geological 
 epoch; and that certain land and fresh-water shells have remained nearly the same, from the time when, as far as is known, they first appeared. It is not an insuperable difficulty that Foraminifera have 
 not, 
 ...| epoch; and that certain land and fresh-water shells have remained nearly the same, from the time when, as far as is known, they first appeared. 1872 |  | period, although no explanation can be given of this fact. 1866 |  | epoch. 1869 | 
as insisted on by Dr. Carpenter, 
 progressed in organisation since even| OMIT 1869 1872 |  | progressed in organisation, 1866 | 
the Laurentian 
 epoch;| progressed in organisation since even 1869 1872 |  | since that most ancient of all epochs 1866 | 
for some organisms would have to remain fitted for simple conditions of life, and what 
 could be better fitted| epoch; 1869 1872 |  | formation of Canada; 1866 | 
for this end than these lowly organised Protozoa? ↑| could be better fitted 1869 1872 |  | better 1866 | 
Such objections as the above would be fatal to 
 my 
 view, 
 if it| 1 blocks not present in  1859 1860 1861 1872; present in  1866 1869 |  | It is no great difficulty that fresh-water shells, as Professor Phillips has remarked, 
have remained almost unaltered from the time when they first appeared to the present day; but in this case we can see that 
these shells will have been subjected to less severe competition than the molluses 
which 
inhabit 
the far 
more extensive area of the sea with its innumerable inhabitants. | 
included advance in organisation as a necessary contingent.  They would 
 likewise be fatal, if the above| if it 1872 |  | which 1866 1869 | 
Foraminifera, for instance, could be proved to have first come into existence during the Laurentian epoch, or 
 the above Brachiopods| likewise be fatal, if the above 1872 |  | be fatal to my view if 1866 |  | likewise be fatal to my view if 1869 | 
during the 
 Cambrian| the above Brachiopods 1872 |  | Brachiopods 1866 1869 | 
formation;| Cambrian 1869 1872 |  | lower Silurian 1866 | 
for 
 in 
this 
 case,| formation; 1869 1872 |  | formations; 1866 | 
there would not have been time sufficient for the development of these organisms up to the standard which they 
 had 
then reached.  When 
 ..
advanced up to any given point, there is no 
 necessity,| case, 1869 1872 |  | were proved, 1866 | 
on the theory of natural 
 selection,| necessity, 1872 |  | necessity 1866 1869 | 
for their further continued progress; though they will, during each successive age, have to be slightly modified, so as to hold their places in relation to 
 slight changes in their conditions.| selection, 1872 |  | selection 1866 1869 | 
The foregoing| slight changes in their conditions. 1872 |  | their changing conditions of life. 1866 |  | the changing conditions of life. 1869 | 
objections hinge on the question whether we 
 really know how old| The foregoing 1872 |  | All such 1866 1869 | 
the world 
 is, and at what period| really know how old 1869 1872 |  | have any sufficient knowledge of the antiquity of 1866 | 
the various forms of life first appeared; and this may 
 well be| is, and at what period 1872 |  | and of the periods when 1866 |  | is, and at what periods 1869 | 
disputed.| well be 1872 |  | be boldly 1866 |  | be 1869 | 
 | 
| The problem 
 whether organisation on the whole has advanced is in many ways excessively intricate.  The geological record, at all times imperfect, does not extend far enough back, 
 ...| whether organisation on the whole has advanced is 1866 1869 1872 |  | is 1861 | 
to show with unmistakeable clearness that within the known history of the world organisation has largely advanced.  Even at the present day, looking to members of the same class, naturalists are not unanimous which forms 
 ought to be ranked as| OMIT 1872 |  | as I believe, 1861 1866 1869 | 
highest:| ought to be ranked as 1872 |  | are 1861 1866 1869 | 
thus, some look at the selaceans or 
 sharks,| highest: 1861 1872 |  | to be ranked as highest: 1866 1869 | 
from their approach in some important points of structure to 
 reptiles,| sharks, 1866 1869 1872 |  | sharks 1861 | 
as the highest fish; others look at the teleosteans as the highest.  The ganoids stand 
 intermediate| reptiles, 1866 1869 1872 |  | reptiles 1861 | 
between the selaceans and teleosteans; the latter at the present day are largely preponderant in number; but formerly selaceans and ganoids alone existed; and in this case, according to the standard of highness chosen, so will it be said that fishes have advanced or retrograded in organisation.  To attempt to compare 
 members of distinct types in the scale of highness| intermediate 1861 1866 1872 |  | in- termediate 1869 | 
seems| members of distinct types in the scale of highness 1872 |  | in the scale of highness members of distinct types 1861 1866 1869 | 
hopeless;| seems 1861 1866 1872 |  | seemed 1869 | 
who will decide whether a 
 cuttle-fish| hopeless; 1872 |  | hopeless: 1861 1866 1869 | 
be higher than a bee— that insect which the great Von Baer believed to be "in fact more highly organised than a fish, although upon another type"?  In the complex struggle for life it is quite credible that crustaceans, 
 ..| cuttle-fish 1866 1869 1872 |  | cuttlefish 1861 | 
not very high| ..... 1866 1869 1872 |  | for instance, 1861 | 
 |