1887 | s Zoology. 387 
mushroom coral occurring at the island of Diego Garcia. He 
did not succeed in finding the budding phase which has been 
described by Moseley, nor did he find any ova or spermatozoa. 
S 
shows that in these forms the tentacles are arranged in circles, 
there being seven circles in his species which correspond to the - 
seven orders of septa. In describing the internal structure Mr. 
layer is frequently called mesoderm, but it is far from proven 
that it is homologous with the layer called by that name in the 
higher Metazoa. The new term signifies middle jelly, and hence 
corresponds to the terms Gallertsubstanz and Gallertanlage of the 
Germans. The mesenteries are described, together with the mes- 
enterial filaments, which, by the way, our author has not seen 
protruded from the cinclides in the species studied by him. In 
of the animal to the skeleton are Fah, as confirmative of Von 
Koch’s views of the formation of the la 
The Life-History of the Hydromeduse.—Under this title Dr. 
W. K. Brooks presents an extensive paper in the third volume of 
the Memoirs of the Boston Society of Natural seat illustrating 
his points by eight plates. He describes the life-histories of 
Cunocantha, Liriope, Turritopsis, and Eutima, four genera which 
are taken as representatives of as many groups of Hydromeduse. 
Hydrozoa; a view diametrically opposite from that usually held. 
The various types of alternation of generations exhibited by 
these forms are placed in their proper sequence, and it is pointed 
out that, on the supposition that the primitive hydrozoan had a 
hydra-like condition, the modifications exhibited are utterly inex- 
plicable, while, if the reverse be assumed, these alternations are 
readily seen to be the results of a free swimming ancestral stage. 
The existence of a true gastrulation in the Ccelenterates is ques- 
tioned. A critical review of the literature of the development of 
the Hydromedusz is given. 
Hydra inside out.—Trembley’s oft-described experi- 
ment of turning the fresh-water Hydra inside out has but rarely 
been repeated, Professor Mitsikuri, of Tokio, being the only per- 
son who had been successful until a recent date. According to 
the accounts, the Hydra in this condition lived as well as before, 
its digestive layer functioning well as skin, while the skin took 
VOL, XXI,—NO, 4. 26 
