30 Dana on the Classification of Animals 
are mainly the same as in passing from the first to the second 
under the Apipens. In passing to the third, there are the semt 
dilutive, the larves being aquatic; and the defunctivnative, the 
mouth in the adult failing mostly of the organs and function 
of feeding. 
The same potential method, which distinguishes Hymenoplers 
from Dipters, or the two highest subdivisions of Apipens, also 
distinguishes the two highest of Amplipens, or Lepidopiers and 
\Homopters, and the two highest of Pterometasthenics, or Coleop- 
ders and Hemipters. 
It is not necessary to continue these illustrations further. 
From the above review of the relations of the successive stages 
roups, it is seen that the distinctions between them are 
throughout strictly ordinal, taking the word in its primary 
sense; that is, all, from the highest to the lowest, are distinc 
tions in rank, 
