Tusk-shells^ Mail-shells, and Limpets 197 



the manufacturer of fancy articles. Instead of 

 the central or marginal slit, such as we have seen 

 in the Keyhole and Slit-limpets, the Ormer has a 

 long spiral series of round holes. As the creature 

 grows the oldest of these perforations are suc- 

 cessively filled up, the last remaining open serving 

 as an anal aperture; whilst the others admit fresh 

 supplies of water to the pair of branchial plumes, 

 of which the left plume is the larger. Filaments 

 from the mantle also pass through these holes, and 

 doubtless serve as sense organs. The animal has 

 a broad head, from which a short snout protrudes. 

 The tentacles are long and thread-like, connected 

 at their base by a fringed lobe, and at their outer 

 bases are placed the stalked eyes. The large fleshy 

 foot is fringed by two rows of delicate filaments, with 

 green tubercles between. The animal creeps along 

 after the manner of a Limpet, and, like that species, 

 rests with the margins of the shell pressed against 

 the rock, from which, however, rats and birds con- 

 trive to force it. 



Curled Slit - shell {Scissiirella crispata). The 

 minute thin white shell of this mollusk shows an 

 advance towards the spiral form of the snails. The 

 last or body-whorl forms the greater part of the 

 shell, but instead of being spread out and shallow, 

 as in the Ormer, the sides are contracted, and when 

 the animal retires within the orifice is closed by a 

 thin oval operculum. In adult specimens the margin 

 of the shell is slit in front. The animal has a 

 rather long foot, a prominent head, and a pair of 

 long fringed tentacles with the eyes at their base. 

 Alono; each side of the foot there are two short 



