Zoology').) who may have written here, as a Portuguese proverb says
"straight in crooked lines."* (* "Deos escrive direito em linhas
tortas." To read this remarkable writing we need the spectacles of
Faith, which seldom suit eyes accustomed to the Microscope.) I cannot
but think that we can scarcely speak of a general plan, or typical mode
of development of the Crustacea, differentiated according to the
separate Sections, Orders, and Families, when, for example, among the
Macrura, the River Crayfish leaves the egg in its permanent form; the
Lobster with Schizopodal feet; Palaemon, like the Crabs, as a Zoea; and
Peneus, like the Cirripedes, as a Nauplius,--and when, still, within
this same sub-order Macrura, Palinurus, Mysis and Euphausia again
present different young forms,--when new limbs sometimes sprout forth as
free rudiments on the ventral surface, and are sometimes formed beneath
the skin which passes smoothly over them, and both modes of development
are found in different limbs of the same animal and in the same pair of
limbs in different animals,--when in the Podophthalma the limbs of the
thorax and abdomen make their appearance sometimes simultaneously, or
sometimes the former and sometimes the latter first, and when further in
each of the two groups the pairs sometimes all appear together, and
sometimes one after the other,--when, among the Hyperina, a simple foot
becomes a chela in Phronima and a chela a simple foot in Brachyscelus,
etc.

And yet, according to the teaching of the school, it is precisely in
youth, precisely in the course of development, that the "Type" is mostly
openly displayed. But let us hear what the Old School has to tell us as
to the significance of developmental history, and its relation to
comparative anatomy and systematic zoology.

Let two of its most approved masters speak.