270 Notes on the derivation of winged insects through several lines etc. 
gota. Closely associated with the Dicelluro-Dermaptera line, is the 
Dicelluro-Coleoptera line, leading from the Japyx-like forms to the 
Coleoptera. 
Certain points of similarity between the Thysanura (as repre- 
sented by Lepisma and Machilis) and the my-flies, or Ephemeroidea, 
suggest that there may have been a Tihysanuro-Ephemeroidea line of 
descent from the Apterygota to the Pterygota, in addition to the other 
lines mentioned above. Furthermore, it is extremely probable that 
a further study of the more primitive representatives of the Apterygota 
and the Pterygota, and the bringing to light to new forms (such as 
the recently discovered Myrientomata) will disclose still other lines of 
descent leading from the primitively wingless to the winged insects, sO 
that the group Pterygota may be considered as in a sence a „poly- 
phyletic“ one. 
It is quite obvious that recent pterygote insects cannot be the 
descendents of apterygote forms now living, since both groups have 
diverged from the common stem, and the various members of the two 
groups have followed their own lines of development, some becoming 
more profoundly modified than others. On the other hand, it is equally 
true that a few representatives of each group, although modified in 
some respects, have nevertheless retained certain very primitive 
characters, which are of great phylogenetic-value in tracing the ancestry 
of the two groups — a point which is not given sufficient weight by those 
who seek to discredit all attempts to derive the Pterygota from ancestors 
simjlar to the apterygote forms. 
As an objection to the theory of the descent of the Pterygota 
from apterygote forms, it has been stated that certain branches of the 
Apterygota have reached a higher degree of specialization, or have 
become more profoundly modified; than the lover Pterygota; but I fail 
to see wherein this has any bearing upon the fact that still other 
branches of the Apterygota have remained in a remarkably primitive 
condition. It is self-evident that an off-shoot from any group of 
animals may become highly modified, or adapted in a certain direction, 
while others of that group (usually few in number) may remain but 
slightly changed from the ancestral type. If this were not true, the 
evolutionists would have but little material to work upon! | 
A somewhat similar objecetion raised by the opponents of this 
theory, is that in certain particular features (e.g. the modified mouth- 
parts) even the most primitive of the Apterygota may be more highly 
specialized than the lower pterygote forms are, so far as these particular 
features are concerned. This, however, should not outweigh the fact 
that in other respects, the lower forms of the Apterygota are far more 
primitive than the lover Pterygota, and have even retained certain 
ancestral characters strongly suggestive of the Myriopoda. 'Throughout 
the realm of Zoology, we find that animals which have retained certain 
very primitive characters, may be highly specialized in other regards, 
since all living things must adapt themselves in some respects at least, 
to differences of environment. This fact is well illustrated by such 
forms as Amphioxus, which is highly specialized in some respects, yet 
this fact does not detract from the phylogenetic value of those very 
primitive characters which it still retains. 
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