[21] OYSTER CULTIVATION IN THE NETHERLANDS. 1021 
3. Thoracostracans. 
a. Macrourans: 
Homarus vulgaris Bel. One specimen was found on the 
Yersche oyster bed. 
Crangon vulgaris Fabr. Below Wemeldinge, in the Eastern 
Scheldt. 
b. Anomurans: 
Pagurus bernhardus Lin. Found here and there in the East- 
ern Scheldt. 
¢. Brachyurans: 
Carcinus menas lL. Very common on the oyster grounds. 
Hyas coarctatus Leach, var. A dark-red variety with a 
peculiarly felt-like body was found once. 
APPENDIX: Pycnogonida. 
Pycnogonum litorale, Strom. Some specimens were found near Kat- 
tendijke, below Wemeldinge, and in some other places. 
V.—MOLLUSKS. 
As has already been said at the end of our private report, only the 
most common kinds of mollusks are observed here. As relating to 
this part of our investigation, we give below a letter from the secre- 
tary of the commission, dated November 9, 1881, and addressed to the 
superintendent of the Scheldt and Zeeuww-stream fisheries: 
LEIDEN, November 9, 1881. 
To the Superintendent of Fisheries in the Scheldt and the Zeeww-stream, at 
Tholen: 
In reply to your letter No. 6402, of June 7, 1881, and the one further 
explaining it, of 12th July, 1881, No. 6482, the Commission of the Zoo- 
logical Station has the honor to report as follows: : 
The inquiry addressed by you to the Commission relates to the oceur- 
rence of the “ Drill”* on oysters imported from Arcachon and planted- 
on Herkingsche Banks. As youareof opinion that the “ Drill” has not 
been found in our waters till now, you have requested us to make an 
investigation of the subject, with the view to ascertain whether this 
animal has been introduced with the oysters referred to, and if so, has 
of course remained alive during the transportation. 
On the 14th July, 1831, I personally visited the Herkingsche Banks, in 
company with one of your officers. Thanks to the kind aid of Messrs. 
van den Berg, who rent several lots on these banks, we were enabled to 
examine on some of these lots everything which, by means of a scraper, 
had been brought up from the bottom in our presence. I examined on 
*The French word ‘‘Perceur” is given in the original, no Dutch translation of it 
having been attempted. Mr. Ryder translates it by this word “ Drill.’—TRANSLATOR, 
