338 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
condition. The medusa-bud does not reach the condition of growth necessary 
for locomotion, and the sexual products are liberated in the immediate vicinity ; 
— herein lies a point relating only to the reproduction of the genus, not of 
sufficient taxonomic value to separate otherwise closely allied forms. Whether 
medusa or sporopliore, therefore, is a question of importance only for the species 
in question, but without importance in fixing relationship to any other forms. 
It is only changed conditions of existence that can affect changes in the tro- 
pliosome, and these changes are of phylogenetic value. The sexual products do 
not arise in the medusa, but in the trophosome — the medusa is only an 
apparatus for distributing them over a wide area. Their form also is not the 
result of the completely different mode of life from that of the nutritive polyp 
but in all essentials depends upon the form of the latter. The medusae change 
step by step only as do the polyps, and no sufficient differences exist to distin¬ 
guish Cory lie and Syncoryne. 
The principle by which Schneider divides his genera may be 
expressed as follows : — 
A species must be considered as a sharply circumscribed group of individ¬ 
uals which can be safely distinguished from all others. All species form an 
unbroken chain with a great number of side branches; this chain often appears 
incomplete and with many gaps owing to our incomplete knowledge. The 
groups of species so distinguished from all other groups are the genera. The 
chief aim, therefore, of the systematist should be, not to create new genera, but 
to show the relationships of species to each other. Wherever we find transi¬ 
tional forms between groups of species, the artificial bounds of one should be 
stretched until, if necessary, 100 or 500 or more species are relegated to a single 
genus. The richer the genus is in species, — that is, the more forms we can 
place in close phylogenetic connection, — the nearer we come to the hypothetic 
ideal of the unity of animal forms. But the more we split up species into 
genera the more difficult does this become, although such splitting is of unques¬ 
tionable value in the handling of a group ; but it must always be borne in mind 
that a word like Syncoryne, for example, represents nothing but a certain num¬ 
ber of closely allied species of one far-reaching genus. 
The Puget Sound forms vary somewhat from A. gravata Hincks, 
but more especially in the size. The British form is very small, 
u only about a quarter of an inch in height,” whereas the western 
forms are from J to § of an inch (12 to 18 mm.). 
When alive the trophosome is colored a delicate rose, due, 
according to Agassiz, to colored granules lining the digestive 
cavity and chymiferous tubes. 
Habitat. Found growing on the edge of wharves and sunken 
logs, and floats, in great quantities at Bremerton in June, the mass 
having a delicate rose tinge. England (T. S. Wright; T. H. 
