190 PECTINIBRANCHIATA.—NATICAD. 
which the hoof-like body assumes, which fit it for 
lying on loose sand, without becoming deepl 
buried in it.”** I am inclined to believe that the 
original form of this egg-mass is that of a very 
broad ribbon, attached by one edge to a rock, like 
that of a Doris, in a spiral curve, the upper edge 
of the ribbon leaning outwards a little, so as to 
resemble a cup, and that the likeness to a horse- 
hoof which Professor Harvey alludes to, and which 
I have myself observed, is seen only when the 
ribbon is torn away by the dredge, and turned 
upside-down. This curious mass of eggs was 
considered to be a zoophyte by the earlier natu- 
ralists, and was characterised as such by Gmelin, 
under the name of Flustra arenosa. Its true 
nature was first suspected by Mr. Boys, and was 
fully proved by Mr. Hogg, in 1833, who hatched 
the Natica from it. 
The species of this genus are all carnivorous, 
boring holes into other shells and devouring their 
contents. Dr. Gould asserts that they are very 
voracious, and play a conspicuous part in devouring 
the dead fish and other animals which are thrown 
up by the tide. The small circular holes with 
which bivalve shells are often drilled, are the work 
of these snails, and made by them to gain an 
entrance to the animal apparently so well secured 
against such a foe. The foot can be expanded so 
as to envelope completely the objects on which they 
prey, for a long retention of it in its grasp is 
necessary, from the slowness with which they work 
their auger or spiniferous tongue. 
* Sea-Side Book, p. 33. + Linn. Trans. 18338. 
+ Invertebr. of Massachusetts, 232. 
