By looking at the diagram we can see that if many of the extinct 
 forms, | forms, 1859 1860 1861 1866 1869 |  | forms 1872 |  
  
supposed to be 
 embedded | embedded 1859 1860 1861 1866 1869 |  | imbedded 1872 |  
  
in the successive formations, were discovered at several points low down in the series, the three existing families on the uppermost line would be rendered less distinct from each other.  If, for instance, the genera 
a
1
, 
a
5
,  
a
10
,
 | 
a
10
,
 1859 1860 1861 1866 1869 |  
| 
a
10
,
 1872 |  
   f
8
, 
m
3
,  
m
6
,
 | 
m
6
,
 1859 1860 1861 1866 1869 |  
| 
m
6
,
 1872 |  
   m
9
, 
were 
 disinterred, | disinterred, 1859 1860 1861 1869 1872 |  | distinterred, 1866 |  
  
these three families would be so closely linked together that they probably would have to be united into one great family, in nearly the same manner as has occurred with ruminants and 
 certain pachyderms. | certain pachyderms. 1861 1866 1869 1872 |  | pachyderms. 1859 1860 |  
   Yet he who objected to 
 call | call 1859 1860 1861 1866 1869 |  
| consider as intermediate 1872 |  
  
the extinct 
 genera, | genera, 1859 1860 1861 1872 |  | genera 1866 1869 |  
  
which thus 
 linked | linked 1859 1860 1861 1866 1869 |  | link together 1872 |  
  
the living genera of three 
 families | families 1859 1860 1861 1866 1869 |  | families, 1872 |  
  
 together, intermediate in character, | together, intermediate in character, 1859 1860 1861 1866 1869 |  
| OMIT 1872 |  
  
would be 
 justified, as | justified, as 1859 1860 1861 1866 1869 |  
| partly justified, for 1872 |  
  
they are intermediate, not directly, but only by a long and circuitous course through many widely different forms.  If many extinct forms were to be discovered above one of the middle horizontal lines or geological formations— for instance, above No. VI.— but none from beneath 
 this | this 1859 1860 1861 1869 1872 |  | his 1866 |  
  
line, then only 
 the | the 1859 1860 1861 |  the 1866 1869 1872 |  
  
two 
 families | families 1859 1860 1861 |  
| of the families (those 1866 1869 1872 |  
  
on the left 
 hand | hand 1859 1860 1861 |  | hand, 1866 1869 1872 |  
  
 (namely, | (namely, 1859 1860 1861 |  (namely, 1866 1869 1872 |  
  
 
a
14
,
 | 
a
14
,
 1859 1860 1861 1866 1872 |  
| 
a
14
,
 1869 |  
  
&c., and 
 
b
14
,
 | 
b
14
,
 1859 1860 1861 1866 1872 |  
| 
b
14
,
 1869 |  
  
&c.) would have to be united into 
 one | one 1859 1860 1861 |  | one; 1866 1869 1872 |  
  
 family; | family; 1859 1860 1861 |  family; 1866 1869 1872 |  
  
and 
 
the two other families (namely,
a
14
to
f
14
now including five genera, and
o
14
to
m
14
) would yet remain distinct.
 | 
the two other families (namely,
a
14
to
f
14
now including five genera, and
o
14
to
m
14
) would yet remain distinct.
 1859 1860 1861 |  
| there would remain two families, which would be less distinct from each other than they were before the discovery of the fossils. 1866 1869 1872 |  
  
↑| 1 blocks not present in  1859 1860 1861 1866; present in  1869 1872 |  |  So again, 
if the three families formed of eight genera 
(
a
14  
to 
m
14
),  on the uppermost line, be supposed to differ from each other by half a dozen 
important characters, then the families which existed at the period marked VI. would certainly have differed from each other by a less number of characters; for they would at this early stage of descent have diverged in a less degree from their common progenitor. 
 |  
   
These two families, however, would be less distinct from each other than they were before the discovery of the fossils. 
 If, for instance, we suppose the existing genera of the two families | If, for instance, we suppose the existing genera of the two families 1859 1860 1861 |  
| 
So again, if the three families formed of eight genera (
a
14,
to
m
14
), on the uppermost line, be supposed
 1866 |  
  
to differ from each other by 
 a dozen characters, in this case the genera, | a dozen characters, in this case the genera, 1859 1860 1861 |  
| half a dozen important characters, then the families which existed 1866 |  
  
at the 
 early | early 1859 1860 1861 |  early 1866 |  
  
period marked 
 VI., | VI., 1859 1860 1861 |  | VI. 1866 |  
  
would 
 differ | differ 1859 1860 1861 |  
| certainly have differed from each other 1866 |  
  
by a 
 lesser | lesser 1859 1860 1861 |  | less 1866 |  
  
number of characters; for 
 at | at 1859 1860 1861 |  
| they would at 1866 |  
  
this early stage of descent 
 they | they 1859 1860 1861 |  they 1866 |  
  
have 
 not | not 1859 1860 1861 |  not 1866 |  
  
diverged in 
 character from the | character from the 1859 1860 1861 |  
| a less degree from their 1866 |  
  
common 
 progenitor | progenitor 1859 1860 1861 |  | progenitor. 1866 |  
  
 of 
 the | the 1859 1860 1861 |  the 1866 |  
  
 order, | order, 1859 1860 1861 |  order, 1866 |  
  
 nearly | nearly 1859 1860 1861 |  nearly 1866 |  
  
 so 
 much | much 1859 1860 1861 |  much 1866 |  
  
 as 
 they | they 1859 1860 1861 |  they 1866 |  
  
 sub- sequently | sub- sequently 1861 |  | subsequently 1859 1860 |  sub- sequently 1866 |  
  
 |