390 General Notes. {April 
So-called eyes have often been described in the Protozoa. The 
latest instance is that of Gymnodinium polyphemus, described by 
Pouchet at a recent meeting of the French Academy. In this 
species of Flagellate there is described a strongly-refringent lens 
seated in a cup of black or red pigment. The lens arises from 
the fusion of several refractive globules and the pigment-layer 
or choroid from the similar coalescence of pigment-granules. 
The animal, in swimming, always moves “ eye” forwards. 
SPoNGEs.—Students of the sponges are under a heavy debt to 
Dr. G. C. J. Vosmær, who has just completed the volume on the 
Porifera in Bronn’s “ Klassen und Ordnungen der Thierreichs.” 
his work forms the only general account of the sponges, and 
, will form a valuable book in the library of every naturalist. 
Carter claims that the sponges recently described from the 
fresh-water fauna of Central Europe and Southern Russia as be- 
longing to the genera Dosilia and Ephydatia in reality are mem- 
bers of the genus Carterius originally described by Mr. Potts 
from Fairmount Park, Philadelphia. 
CŒLENTERATA.—The reef-corals of the “Challenger” Expe- 
dition are described in vol. xvi. of the Reports by J. J. Quelch. 
The collection contained two hundred and ninety-three species, 
seventy-three of which, all but two from the Pacific and Indo- 
tr 
ids, absent in some Rugosa; some Cyathophyllide have no 
indication of a tetrameral type, while in some Astræids the septa 
are not multiples of six; the rugose character of only two sizes 
of septa is present in some Astraidz and absent in some Ru- 
tend towards the conclusion that atolls and barrier-reefs owe 
ir appearance at the surface to a movement of elevation. 
o 
twenty fathoms below the surface, and Mr. Guppy believes that 
they cannot come within the range of the constructive power of 
the breakers without the aid of an elevatory movement, To the 
_ breakers he (with Semper) ascribes the atoll form, the convexity 
being towards the prevailing currents. Large atolls begin to 
assume their shape bélow the surface. He claims to have in- 
dependently worked out the same conclusion to which Le Conte 
ane Floridan ; 
=, a : ide 
by the muddiness and on the. other by the depth of the water. 
