456 TRANSFORMATIONS OF INSECTS. 
such as the mandibles and the maxillz, bear a close resemblance 
of form to the same organs in adult Crustacea, of an order lower 
than the parent of these.” (Spence Bate.) 
Many years since, Erdl stated that the young lobster was of 
the same shape as the adult, and the metamorphosis of these 
common Crustacea has therefore been denied. This opinion was 
strengthened by the observation that the European fresh-water 
cray-fish and the West Indian land crab quit the egg with the full 
number of jointed limbs, and, indeed, in the likeness of their parents. 
All these are stalk-eyed Crustacea; and what could be more natural 
than that they should all have the same method of evolution? It 
is most remarkable how dangerous it is to reason by analogy in 
natural history, and to indulge the imagination in science. Gerbe, 
Spence Bate, and Couch, however, have proved that the statement 
of Erdl is not consistent with facts. Spence Bate noticed, in one 
of his reports to the British Association for the Advancement of 
Science, that “common as the European lobster (Homarus 
marinus) is, it is very remarkable that a very young specimen has, 
as far as I know, never been met with.” He offered a reward for 
a very small specimen, but never received one less than three 
inches long from the tip of the spine over the head (rostrum) to 
the end of the tail-piece (telson). By hatching the eggs, however, 
he obtained the first stage of lobster life, but could not keep the 
young alive until their metamorphosis into the second. Having 
obtained also a young lobster, eight days old, from the Hamburg 
aquarium, he was able to state that not only is the young hatched 
in a form distinct from that of the parent, but that it retains that 
form for some time after its birth. 
The figures on the next page are by M. Gerbe, and the descrip- 
tions of Spence Bate prove that they are tolerably correct. 
The egg is about one-tenth of an inch in diameter, and contains 
a yolk of a dark, almost black, green colour. The central dark eye 
of the embryo is distinctly seen in the earlier days of development, 
but it is lost when the animal escapes from the egg. At this 
period the young Zoéa has a short pointed (Fig. 2) rostrum that 
is at first bent back, two large eyes situated under the front 
part of the head, and two antenna. It has mandibles without 
joints, two pairs of maxille, the third not being yet developed, and 
