nce of as
many organisms as it presents morphological segments.

Professor Haeckel adduces the fossil _Crossopodia_ and _Phyllodocites_
as examples of the Annelidan forms, by the coalescence of which
the Echinoderms may have been produced; but, even supposing the
resemblance of these worms to detached starfish arms to be perfect,
it is possible that they may be the extreme term, and not the
commencement, of Echinoderm development. A pentacrinoid Echinoderm,
with a complete jointed stalk, is developed within the larva of
_Antedon_. Is it not possible that the larva of _Crossopodia_ may have
developed a vermiform Echinoderm?

With respect to the Phylogeny of the _Arthropoda_, I find myself
disposed to take a somewhat different view from that of Professor
Haeckel. He assumes that the primary stock of the whole group was
a crustacean, having that _Nauplius_ form in which Fritz Mueller
has shown that so many _Crustacea_ commence their lives. All the
_Entomostraca_ arose by the modification of some one or other of these
Naupliform "_Archicarida_." Other _Archicarida_ underwent a further
metamorphosis into a _Zoaea_-form. From some of these "_Zoeopoda_"
arose all the remaining Malacostracous _Crustacea_; while, from
others, was developed some form analogous to the existing _Galeodes_,
out of which proceeded, by gradual differentiation, all the
_Myriapoda, Arachnida,_ and _Insecta_.

I should, be disposed to interpret the facts of the embryological
history and of the anatomy of the _Arthropoda_ in a different manner.
The _Copepoda_, the _Ostracoda_, and the _Branchiopoda_ are
the _Crustacea_ which have departed least from the embryonic or
_Nauplius_-forms; and, of these, I imagine that the _Copepoda_
represent the hypothetical _Archicarida_ most closely. _Apus_ and
_Sapphirina_ indicate the relations of these Archaeocarids with the
_Trilobita_, and the _Eurypterida_ connect the _Trilobita_ and the
_Copepoda_ with the _Xiphosura_. But the _Xiphosura_ have such close
morphological relations with the _Arachnida_, and especially with the
oldest known Arachnidan, _Scorpio_, that I cannot doubt the existence
of a genetic connection between the two groups. On the other hand, the
_Branchiopoda_ do, even at the present day, almost pass into the
true _Podophthalmia_, by _Nebalia_. By the _Trilobita_, again, the
_Archicarida_ are connected with such _Edriophthalmia_ as _Serolis_.
The _Stomapoda_ are extremely modified _Edriophthalmia_