450 
TRANSFORMATIONS OF INSECTS. 
the Zoea , which succeeds. Like the larvae of those spiders which 
undergo metamorphosis they have six legs — the three pairs of 
extremities which characterise the true insects as a class. More- 
over, the mouthpieces of the immature representatives of the 
different classes are of the same number. Fritz Muller points this 
out with great force, when arguing respecting the interesting 
question of the origin of the classes included under the A rticulata 
from a common ancestry, and remarks, moreover, that the true 
insects, like the Zoece of Crustacea have no appendages to the 
abdomen, and that both have mandibles without palpi. When the 
habits, transformations, and structures of the water insects are 
considered, and especially those of the wonderful water larvae of 
the Hydrocampa moth, and the Ephemera larva, there is no diffi- 
culty in believing in the descent of the more complicated terres- 
trial forms of insects from the Nauplii or Zoece of early fresh 
water Crustacea. 
Fritz Muller has pointed out that the Orthoptera with larvae 
which have eleven segments in the abdomen (and not nine 
as in the Lepidoptera larvae) agree with the rudimentary prawns 
— the Zoece , and with the higher Crustacea , in the number 
of their body segments. He notices, moreover, that in the 
Orthoptera and the Crustacea the egg orifice and the vent 
are placed on different segments, and not on one particular 
ring. 
The oldest known insects are Orthoptera , or the closely allied 
N europtera and Coleoptera. It is, therefore, important to remember 
that the majority of the Orthoptera leave the egg not in a more 
or less embryonic condition, but as larvae which resemble greatly 
and have the same habits as the adult forms. The development of 
wings proceeds, and the generative processes are adopted, and that 
is nearly all that takes place between birth and adult age, except 
simple growth. The growth progresses without distinct states, 
and is accompanied by no marked phases of transformation. All 
this hints at the complete metamorphosis of other insects being 
an acquired gift during the struggle for existence ; and when 
the structural relations between the Orthoptera and the Zoece of 
the Crustacea are considered, the origin of the two articulate or 
insect forms from some older kind of Cmstacea commends itself to 
