The shell will be readily recognised without an illustration. In form somewhat resembling the human ear, the shell possesses properties which can be found in no other specimen of the order. For the purposes of the engraver, the several parts are called by totally different names, according as the workman came from Naples or Rome; but without entering into a discussion of the origin of these, I propose to give a few plain names to the several parts, in order to enable a worker to order the particular piece or portion which is required. Thus, the several parts are the back of the shell, the back of the Lip, the Dome, and the Comb, the Mouth of the shell, the Lip, and the Face or Body.

The piece in the upper portion of the Dome is the most valuable, because in that there is no variation of colour. Pieces cut from all other portions of the shell vary slightly in depth of colour, the colour deepening in tone as the mouth is approached. A piece suitable for a brooch cut out of a Black Helmet would be worth 5s.; but with regard to other shells the prices vary as set out in the following list. Other portions of the Dome are used for brooches; but the choicest piece is the one named. The Comb, having been cut off, is cut up into separate knobs, and these are worked into heads which are required to stand out in bold relief. The back edge is rarely worked, and may be regarded as waste. The Lip is the next important portion, and this is suitable for the carved handles of paper-knives, for umbrella-handles, or for paper-weights. A full length figure of classic form may be carved in the Lip, with admirable results, so as to command a high price. The Lip is perhaps more frequently cut into pieces between the raised edges which run at right angles to the course of the mouth, and are used for carving fish or birds, or any form requiring a portion in high relief. When the Dome has been cut through, a second shell appears immediately below, and this is remarkable for having three distinct layers, brown or red forming the surface, white the centre, and brown or red the ground. Such a piece is necessary where the design involves ornaments in the hair or a helmet on the head of a warrior.

The shell is cut open by means of a tin wheel revolving on a spindle in the ordinary way by means of a treadle. Above the wheel is a sloping dish coming to a point on which emery powder lies, and above the tray is a small keg of water regulated by a stop-cock, in such a way that as the water trickles down the pan it carries particles of the powder on to the wheel. The workman first cuts off the Lip, then he cuts across, above and below the Comb, and finally cuts down from the point of the Dome to the Comb again. This triangular piece is cut up into as many portions as are required, care being taken first of all to cut out the choicest piece from the upper portion.