440 HALI0TIDJ5. 



the four inner being very large. Head with a short, broad 

 muzzle; tentacles subulate, with the eyes on stout, cylin- 

 drical peduncles at their outer bases, and with a fimbriated 

 lobe, or an emarginate veil, between them. Mantle-margin 

 fissured in front, the left lobe elongated into an anal 

 siphon occupying the anterior perforation of the shell ; 

 gills two, unequal. Foot thick and fleshy, the sides with 

 a double membrane, furnished with serrated lobes and fila- 

 ments on the edges, and continued, anteriorly, in a free 

 crest, under the head. 



Operculum none. 



Shell ear-shaped ; aperture large, nacreous and irides- 

 cent internally, perforated with a series of holes. 



In the family of Haliotidce or " Ear-shells," we find the 

 lingual dentition very similar to that of the Trochidce, the 

 eyes, moreover, are pedunculated, and there are analogous 

 head-lobes and lateral fringes ; there are, however, two 

 branchial plumes, and the muscle of attachment, instead 

 of being crescentic round the mantle, is central and 

 ovate. In the perforated shell and double gill, as well as 

 in the great development of the foot, this family seems 

 to resemble that of FissurellidiP, but the shell is sub- 

 spiral, and the apertui'e is lined with an iridescent nacre. 



Genus HALIOTIS, Linnaeus. 



Foot moderate, not grooved and produced posteriorly. 



Shell depressly ovate, or ear-shaped ; spire small, obtuse, 

 sub-lateral, surface rough, wrinkled, or tubercular ; aper- 

 ture very wide, broader than long, iridescent and pearly 

 within, the left side perforated with a series of holes. 



