300 THE ESSEX NATURALIST.
In contrast with these proportions it is found that collections
by hand of tingles from the foreshore at low water spring-tide
level usually consist in spring and early summer of 100 per cent.
Urosalpinx.
HABITS OF UROSALPINX.
These figures prove that the habits of Urosalpinx are different
from those of Ocinebra and Purpura in the locality of the River
Blackwater. The occurrence of Urosalpinx on the foreshore in
spring and early summer is probably mainly the result of a
spawning migration, for these animals spawn heavily in shallow
water ; but it is also possible that Urosalpinx is attracted to the
foreshore by the oysters which are laid at this tidal level either
for convenience or for rapid fattening. Mr. Louis French informs
me that scores of tingle (Urosalpinx) may be found on oysters
only a day or two after relaying these at the low water level, in
places where tingle could not previously be found. Further
investigations are being made regarding the distribution of these
three tingles in the Blackwater region, and it is anticipated
that interesting new facts may be brought to light.
Recently an American naturalist, Federighi, has studied
the habits of Urosalpinx with a view to eradicating this pest
from the oyster beds. He has found that this oyster-drill con-
gregates—especially in spring—on hard substances on the sea-
bottom, e.g., stones, on which egg-capsules are laid; and from
this observation he has devised a method of trapping the animals
(5). The trap consists simply of a cylindrical cement block, to
the top of which is fastened a line and a buoy. Numbers of these
blocks are placed about the oyster beds and hauled as frequently
as possible, e.g., daily, when the drills which collect upon them
are removed and taken ashore to be destroyed. I have found
* These young Buccinum undatum were included in the sample in error and are not oyster-
drills.