38b MURICIDiE. 



found that the whelk had turned over the mussel and had 

 resumed its operation at its old bore. This I did twice or 

 thrice, with the same result. Giving up the idea of its 

 boring at any other point, I next thought I should like to 

 see how it managed to devour its prey. For this purpose 

 I divided the muscles of the mussel, so that the valves 

 parted, so as to enable me to observe the work of gorman- 

 dizing as it proceeded, but to my surprise the animal gave 

 up all idea of boring when there was an easier method of 

 obtaining food, and so passed its proboscis between the 

 valves. I think this shows that the whelk, when it 

 attacks its prey, seeks out for the part most suitable for 

 its operation, and I believe invariably chooses a point from 

 which the epidermis has been removed previously. A 

 section of the bore, taken during the operation, shows that 

 it is convex, and contradicts the received notion of the 

 operation being performed by the action of the riband, 

 which, being in the centre of the proboscis, would perforce 

 wear the middle of the bore deepest ; but this is not the 

 case. The animal makes no movement of a rotatory kind 

 or otherwise during the operation. It takes about two 

 days to get through the shell, when it eats about two- 

 thirds of a moderate sized mussel, which seems to satisfy 

 hunger for about three weeks." 



This whelk is called Dog-periwinkle on many parts of 

 the coast. It rarely lives below tide-marks ; when it 

 is so found, it is subject to great variation of form and 

 sculpture, in some places becoming more elongated and 

 thinner, in others having the furbelowed laminae beauti- 

 fully developed. It is indeed a most variable shell, and 

 recent conchologists would do well to look at Plate IV. of 

 Mr. Searles Wood's Monograph of Crag Mollusca, and 

 see what strange modifications of form a single species 



