OYSTER-DRILLS IN THE ESSEX ESTUARIES. 303
of experiments, were found to bore into and devour also several
species of acorn barnacles (Balanus). The food of the rough
whelk-tingle, therefore, undoubtedly varies with the habitat
and includes oysters, barnacles, crow-oysters, detritus, and
probably also tubicolous worms and other encrusting marine
organisms. Oysters are thus not an essential food and the
taste for them is apparently acquired.
Fig. 1. Two Living Ocinebra erinacea boring a Large
Brood Oyster (from a photograph by D. P. Wilson).
HABITS OF PURPURA.
The smooth whelk-tingle, like the rough one, is widely dis-
tributed along the Atlantic coast of Europe and is stated (Jefferys,
8) to occur in the Arctic seas of both hemispheres. The food of
this tingle is usually barnacles, limpets (Patella), or mussels, but
any available shelled animals may be attacked and eaten. Spence
Bate and Brotherton observed (loc. cit.) that it took Purpura