for
example, as Mueller says, "quit the egg in a form which is distinguished
from that of the adult insect almost solely by the want of wings," while
the freshly hatched young of the bee, we may add, is farthest from the
form of the adult. It is evident that in the young grasshoppers, the
metamorphoses have been passed through, so to speak, in the egg, while
the bee larva is almost embryonic in its build. The helpless young
maggot of the wasp, which is fed solely by the parent, may be compared
to the human infant, while the lusty young grasshopper, which
immediately on hatching takes to the grass or clover field with all the
enthusiasm of a duckling to its native pond, may be likened to that
young feathered mariner. The lowest animals, as a rule, are at birth
most like the adult. So with the earliest known crustacea. The king
crabs, and in all probability the primeval trilobites, passed through
their metamorphoses chiefly in the egg. So in the ancient Nebaliads
(Peltocaris, Discinocaris and Ceratiocaris), if we may follow the
analogy of the recent Nebalia, the young probably closely resembled the
adult, while the living crabs and shrimps usually pass through the most
marked metamorphoses. Among the worms, the highest, and perhaps the most
recent forms, pass through the most remarkable metamorphoses.

[Illustration: 209. Jaws of Ant Lion.]

Another puzzle for the evolutionist to solve is how to account for the
change from the caterpillar with its powerful jaws, to the butterfly
with its sucking or haustellate mouth-parts. We shall best approach the
solution of this difficult problem by a study of a wide range of facts,
but a few of which can be here noticed. The older entomologists divided
insects into haustellate or suctorial, and mandibulate or biting
insects, the butterfly being an example of one, and the beetle serving
to illustrate the other category. But we shall find in studying the
different groups that these are relative and not absolute terms. We find
mandibulate insects with enormous jaws, like the Dytiscus, or Chrysopa
larva or ant lion, perforated, as in the former, or enclosing, as in the
latter two insects, the maxillae (_b_), which slide backward and forward
within the hollowed mandibles (_a_, Fig. 209, jaws of the ant lion),
along which the blood of their victims flows. They suck the blood, and
do not tear the flesh of their prey. The enormous mandibles of the adult
Corydalus are too large for use and,