ILLUSTRATIVE OF NATURAL SELECTION. 189 
its name, the possession of mammary glands and the 
power of suckling the young. What more reasonable, 
apparently, than to argue that the group in which 
this important function is most developed, that in 
which the young are most dependent upon it, and 
for the longest period, must be the highest in the 
Mammalian scale of organization? Yet this group is 
the Marsupial, in which the young commence suckling 
in a foetal condition, and continue to do so till they 
are fully developed, and are therefore for a long time 
absolutely dependent on this mode of nourishment. 
These examples, I think, demonstrate that we can- 
not settle the rank of a group by a consideration of 
the degree in which certain characters resemble or 
differ from those in what is admitted to be a lower 
group; and they also show that the highest group of 
a class may be more closely connected to one of the 
lowest, than some other groups which have developed 
laterally and diverged farther from the parent type, 
but which yet, owing to want of balance or too great 
specialization in their structure, have never reached 
a high grade of organization. The Quadrumana afford 
a very valuable illustration, because, owing to their 
undoubted affinity with man, we feel certain that they 
are really higher than any other order of Mammalia, 
while at the same time they are more distinctly allied 
to the lowest groups than many others. The case of 
the Papilionide seems to me so exactly parallel to 
this, that, while I admit all the proofs of affinity 
with the undoubtedly lower groups of Hesperide and 
