280 HALIOTID^. 



with pale green, and occasionally speckled with brown, pink, or 

 white : epidermis fibrous, thin, of a light yellowish hue : spire 

 small, somewhat raised : ivlwrls three or four, rapidly increas- 

 ing, and becoming less convex as they recede from the apex : ori- 

 fices from six to eight, roundish ; their sides are raised so as to 

 resemble tubercles : mouth oval : outer lip bevelled to a sharp 

 edge : inner (or pillar) lip broad, flattened, somewhat notched 

 or emarginate at the base in front, and bordered outside by a 

 pink line : inside dark towards the margin, although in other 

 parts splendidly lustrous. L. 4. B. 3. 



Habitat : Rocks and large stones at low water in the 

 Channel Isles ; common. The Devonshire^ Sussex, 

 Scotch, and Irish localities mentioned by Pennant, Da 

 Costa, Laskey, Turton, and Brown must have been 

 from hearsay, and are manifestly wrong. Linne intro- 

 duced this handsome and familiar shell into his ' Fauna 

 Suecica,^ on apparently no better grounds. The prin- 

 ciple of geographical distribution was not then known, 

 and a long time elapsed before it was made a law. Fos- 

 sil in the Sicilian tertiaries (Philippi) . It inhabits the 

 North Atlantic, from St, Malo to the Canary Isles and 

 Azores, the Adriatic, and every part of the Mediter- 

 ranean. 



I include this among our Mollusca, because the 

 Channel Isles are as much an integral part of Great 

 Britain as are the Shetland Isles. The animal rivals 

 the shell in beauty. From Beudant^s experiments it 

 appears that H. tuberculata cannot exist in fresh water. 

 Mr. Daniel detected in its stomach different species of 

 diatoms in considerable quantities, besides many crys- 

 talline substances of the same prismatic hue as its own 

 shell. These last mentioned organisms may have been 

 the spicula of sponges. The number of open orifices in 

 the shell corresponds with that of the tubular folds of 

 the mantle. As the animal grows, the orifices that 



