124 UNIVALVES. HALIOTIS. 



color to what species it appertains. Secondly, as the in- 

 terior of the Haliotides is enamelled with a magnificent 

 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 increased by 

 being wholly or partially uncoated and polished, it is 

 customary to submit it to some such beautifying operation ; 

 V, hich, however, with the surface, at once removes all 

 clue to the attainment of the specific character. 



The exterior of the shell is generally composed of rugae 

 or tuberculations, over which pass approximate elevated 

 striae. In some species, foliations supply the place of tu- 

 berculations, as in the H Midae or Midas' earj the out- 

 side of which is wrinkled, and of a dusky white hue; but 

 the inside is most beautifully iridescent. It is often eight 

 or nine inches long. 



The back of almost the whole of the Haliotides is fur- 

 nished with a row of orifices near the margin; varying 

 in number from eight to thirty-eight; of these from three 

 to seven are generally open, and the rest perfectly closed. 

 There are, however, two exceptions to this general char- 

 acter; for the H. imperforata and H. perversa (whose 

 spire is turned contrary), are entirely void of any orifices. 

 The former, which has an ovate form, with an exserted 

 spire and prickly ribs, is a rare shell. 



The Haliotis tuberculata is found on the British coasts. 

 The H. parva is remarkable for its red or scarlet color, 

 and for having but one large elevated rib or angle on its 

 back. The H. bistriata is peculiar for having a succes- 

 sion of double elevated striae, placed in a transverse direc- 

 tion on the back. The H. pulcherrima is a beautiful and 

 rare shell, from the South Seas. 



The H. iris, (from New Zealand), is celebrated for its 



