UNIVALVES HALIOTIS. 1 03 



surface of iridescent pearl, no great distinction can be 

 made by a reference to that part of the shell. Thirdly, 

 as the beauty of the shell is considerably encreased by 

 being uueoated and polished, so is it also customary to 

 submit it to some such beautifying operation; which, 

 however, ^^ ith the surface, at once removes all clue to 

 the attainment of the generic character. 



The exterior of the Sea-ears is generally composed of 

 rugae or tuberculations, over which pass approximate ele- 

 vated stri-te. In some species, foliations supply the place 

 of tuberculations, as is the case in the Haliotis MidcG 

 or Midas' Ear, the outside of which is wrinkled, and of 

 a dirtyish white complexion ; but the inside is of the most 

 beautiful pearl. It grows to eight or nine inches long. 



The back of almost the w hole of the Haliotides is fur- 

 nished with a row of orifices near the margin ; their num- 

 ber varies from eight to thirty-eight; and out of that 

 number from three to seven are generally open, the rest 

 are perfectly closed. There are, however, two exceptions 

 to this general appearance ; for the Haliotis Imperforata 

 is entirely void of any orifices whatever, as is also the 

 Haliotis Perversa, whose spire is turned contrary. The 

 former is deemed one of the great rarities ; its shell is of 

 an ovate form, imperforate, with an exserted spire, and 

 prickly ribs. 



The Haliotis Tuberculata is the Common Ear, found on 

 the British coasts. The Haliotis Parva, is remarkable for 

 its red or scarlet color, and from its having but one large 

 elevated rib or angle on its back. The Haliotis Bistriata 

 is, on the contrary, peculiar for having a succession of dou- 

 ble elevated striae, placed in a transverse direction on the 

 back. The Haliotis Pulcherrima is a beautiful and rare 

 shell, and is from the South Sea. 



