196 Prof. Carl Claus on the 
extensive, indeed almost unlimited, use of his skill in making 
new and suitable names, is certainly intelligible from the fact 
that he possesses this faculty in a very high degree and has 
developed it, by many years’ practice, into a speciality, in 
which at present no other naturalist can hope to equal him. 
But, although it cannot be denied that the introduction of 
new and appropriate names has many advantages, and is 
especially indispensable for the sake of conformity in the 
schematization of theory and system, it is, however, indis- 
putable that by the continual accumulation of synonyms it 
leads to a nearly unlimited complication of nomenclature, 
causes much confusion, and instead of facilitating investiga- 
tion renders it more difficult. It is therefore only in place 
when moderately exercised where the conditions absolutely 
require it, but when immoderately done without absolute 
necessity decidedly mischievous, and to be rejected at once 
when by it old, equally good names, which have become 
historical by the personality of meritorious authors, are dis- 
placed and removed from science. 
However, our knowledge of forms has been extraordinarily 
enlarged by Haeckel’s work, inasmuch as out of 240 species 
more than 60 were previously unknown, and these for the 
most part belong to new and interesting genera. By this 
astonishing enrichment of the materials the system must also 
have undergone a corresponding complication of form and 
abundance of divisions, and besides new genera new categories 
of higher rank, especially families and subfamilies, have had 
to be established. Unquestionably the special descriptive 
part, which is also of much greater extent, possesses a much 
higher value than the general or “ philosophical” part, which 
is more aphoristically treated in the short introductory chap- 
ters, and which is intended to found the Medusome-theory 
and the system established upon it. Whether in the former 
the author has everywhere hit upon the right course and has 
not often gone too far may even now be justly doubted, and 
will be decided in the future by later investigations. There 
are numerous novelties in connexion with the division of pre- 
existing genera into two or more, and, indeed, on the ground 
of trifling distinctions scarcely applicable as generic characters. 
As examples may be cited the division of Physalia into Phy- 
salia and Caravella and of Alopleota into Alopleota and 
Arethusa, as also the establishment of two subfamilies asso- 
ciated therewith ; further the breaking up of Rhizophysa by 
its different species into the genera Aurophysa, Cannophysa, 
Linophysa, Nectophysa, Pneumophysa, and Rhizophysa, and 
