wy 
[19] OYSTER CULTIVATION IN THE NETHERLANDS. 1019 
Vaginicola crystallina Ehbr., and Cothurnia nodosa Cl. Lachm., besides a 
large number of intermediate forms, were also very common. Besides 
these I noticed a Strombidium and the elegant Halteria pulex Cl. Lachm. 
(without any good reason called Acarella siro by Cohn). 
Of HETEROTRICHZ no trace could be discovered. 
As my knowledge of a number of important varieties is still very de- 
fective, I hope that another prolonged visit to the Scheldt will enable 
me to fill many gaps. 
If. SPONGES.—(Report by Dr. G. C. J. Vosmaer.) 
In the beginning of Juiy, when I had not yet begun my work at the 
station, Dr. A. Horst wrote me, that at Yerseke he had found on the so- 
called collectors a large number of calcareous sponges. Thanks to his 
forethought I am now in possession of a large number of them. When 
later in the season I searched for sponges at Bergen op Zoom, I found in 
Mr. de Meulemeester’s pits the same kind which I recognized as Sycandra 
ciliata (trans. var. coronata), according to Haeckel’s terminology. In ex- 
amining a large number of specimens, among them some very large 
ones (up to 80 millimeters) I became doubtful whether Sycandra ciliata H. 
and coronata H. can be considered as two different species, and whether 
they should not, as in former times, be looked upon as two varieties 
of one and the same species. The circumstance that I had to class all 
the specimens which I examined, under the “transitory variety,” seems 
to speak strongly in favor of the last-mentioned opinion. I hope to con- 
tinue my observations with the view of forming a definite opinion on 
this subject. To whatever kind these sponges may belong, the fact 
that calcareous sponges occur on our coast is entirely new. It is also 
peculiar that all such objects are found on the lower side of the collec- 
tors, and that they therefore hang with their oscule downward. 
Another important discovery was that of another sponge belonging 
to the family of the Chalinea, which is probably identical with.Chalinula 
Jertilis, Kell., 1880. This sponge, which is likewise new in our fauna, 
appears as a light brownish-red crust on the oyster shells, especially on 
the large oysters called “ paardepooten” =“ horse-feet.”. Most of them 
seemed to come from Lot 250, near Yerseke, and some were aiso found 
by me in the “‘ Hendracht” (Lot 18) near Tholen. I hope that I shall be 
able at some future time to give a fuller account of these sponges. 
A kind of sponge, found in many places on our coast, and called by 
Johnston Halichondria panicea—a name which is no longer employed— 
is also found amongst oysters. 
In how far either of these kinds of sponges is healthful or hurtful to 
the oyster, cannot be determined at the present time. 
It. Worms.—(Report by Dr. R. Horst.) 
The varieties of worms mentioned below were found on the oyster- 
beds during the past summer. This list does not, however, pretend to 
