LAMELLAUIA. 179 



II. Lamellaria. — The shell of 

 L. tentaciilata is flat and open^ like a Haliotis ; that of 

 'L.perspicna is more globose, like a Sigaretus. 



Both species are white, being entirely covered by the 

 mantle of the animal. Seen from above, the mantle presents 

 an oval, irregular, convex disc, with a sinus in front ; when 

 turned up the foot is seen, which is oblong and rather scal- 

 loped at the sides; beyond this foot, but still under the 

 mantle, protrudes the head, with the pair of tentacles, bear- 

 ing eyes at their base. 



