342 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 
The scarcity of evidence may also be partly due to the circumstance 
that facts bearing on this point have been, to a great extent, over- 
looked by Naturalists, and not recorded when casually observed ; but 
this, I trust, will no longer be the case now that the attention of 
observers has been drawn towards the subject. 
Asa first contribution I venture to publish the following observation. 
On the 26th of September last I rowed about in a Greenland ¢ kajak’ 
(a very small boat, made of seal-skin, for a single person) near the 
harbour of Grenaa in the Kattegat (between the Baltic and the North 
Sea), and on this occasion I observed MMactra subtruncata, Da Costa, 
floating on the surface of the water to the number of at least several 
hundreds. They were floating in a rather narrow band in a south- 
easterly direction. There was a slight wind from the south-east, and 
the waves were only one to two feet in height. The shells were from 
2 to 7 or 8 mm. in length, tightly closed, and more or less (in most 
cases totally) filled with air. Some of them probably contained 
animals, but these must have been completely dried up. 
I followed the stream of shells from the point where I noticed it, 
a few hundred yards from the shore, towards the place where it 
originated, and I found this to be a bank of sand some 10 to 20 yards 
from the shore, and, at that time, only covered by about 6 inches of 
water. Here the shells were found in a regular layer, and this bank 
had been dry for about two successive days past, there being practically 
no tide in these waters. 
Since in the Kattegat this species only descends to a depth of about 
12 fathoms, it is highly probable that some of the shells would sink to 
the bottom beyond the range of distribution of the living animal. 
I therefore think that this record may be of some interest as an instance 
of what may take place at a great many points off sea-beaches. 
