mals designated by
them. The word _Mollusca_ only meant that the creatures grouped
together had soft bodies, unsupported by internal or external
articulated skeletons; and this character, or, rather, absence of
character, was applied alike to many totally dissimilar creatures. The
term _Articulata_ included not only Linnaeus's insects but a number of
soft-skinned, apparently jointed, worm-like animals such as the leech
and earthworm. Lastly, the name _Radiata_ meant no more than that the
organs of the creatures so designated were more or less disposed
around a centre, as the sepals and petals of a flower are grouped
around the central pistil; and it included animals so different as
the starfish and sea-anemones and Medusae. The names used in the
classification were not only loosely applied but were based on the
most superficial observation, and took no account of the intimate
structures of the tissues and organs of the animals. With slight
modifications, due to individual taste or special knowledge of small
groups, later writers had followed Linnaeus and Cuvier.

It was with a view of the animal kingdom not much clearer than this
that Huxley began his work on the Medusae of the tropic seas. He began
to study them no doubt simply because they were among the most
abundant of the animals that could be obtained from the ship. He made
endless dissections and drawings, and, above all, studied their minute
anatomy with the microscope. They were all placed among Cuvier's
_Radiata_, but, as Huxley said in the first line of his memoir:

"Perhaps no class of animals has been investigated with so little
satisfactory and comprehensive result, and this not for the want
of patience and ability on the part of the observers, but rather
because they have contented themselves with stating matters of
detail concerning particular genera and species, instead of
giving broad and general views of the whole class, considered as
organised upon a given type, and inquiring into its relations
with other families."

He found that fully developed Medusae consisted each of a disc with
tentacles and vesicular bodies at the margins, a stomach, and canals
proceeding from it, and generative organs. He traced this simple
common structure through the complications and modifications in which
it appeared in the different groups of Medusae, in all this work
bringing out the prevailing features of the anatomy in contra