1915] Quantitative Entomology 379 
Thus the production of wings is a specialization least liable 
to have occurred more than once in the history of insects, 
while the suppression of wings is an often recurrent phenomenon. 
Again characters which are of themselves of little moment 
may open the way to other reorganizations of structure of 
highest significance. This development of complex meta- 
morphosis may easily have occurred more than once. The male 
Coccide probably have such a mode of development following 
the most strict definition of the process and the hypermeta- 
morphosis of Meloids is a further extension of practically the 
same kind of specialization, but the development of this mode 
of growth opened the way to the origin of the four largest 
orders. 
To properly estimate the relative phylogenetic significance of 
characters all of these considerations must be comprehended 
in our classification. From this point of view no character 
is important in itself only in its relation to the whole organiza- 
tion of the members of the group. 
Coordination of groups consists of determining which are 
to be considered of equal rank. This is a subject upon which 
there has been, and still is, two very definite tendencies. Ento- 
mologists are in most complete accord for instance as to the 
orders into which perhaps 95% of the species of insects belong 
and “eévertheless, the current) text. boeks vary from. 7° to 37 © 
orders. The same tendency is seen among systematists in 
every group of plants and animals. 
Some naturalists may have the conception that every 
group sprang from a single mutant pair and from the time of 
their mutation the new group existed. The Lepidoptera 
are for instance derived by common consent, from the Trich- 
optera, because chiefly of the almost complete conformity of 
the venation of certain members of the two groups, but there 
are at least two very different types of wings in which this 
perfect conformity is seen which are most easily explained 
by the assumption of a tendency of development seen in a 
series of species in one order giving rise to a series of forms in 
the new group in the same manner as most conceive that 
geographic isolation may bring about two species with parallel 
varieties. The variations being parallel because residual. 
