232 LIFE BY THE SEASHORE. 



snail (Helix), where the eyes are borne at the end of the 

 long tentacles. Most common marine Gasteropods have eyes 

 placed in the position seen in Patella. 



The next limpet we shall consider is a much prettier form 

 than Patella, and in its own area almost as common. To 

 find it we must choose a spring tide, and tramp steadily 

 outwards till we top the last reef, and come down to the 

 sea-meadows where the giant Laminarice flourish. Choose 

 a spot where you can look down on the floating fronds, and 

 you will see that they are spotted with tiny shells of the 

 same tint as the weed, but barred with radiating lines of 

 shimmering blue. The colour is of the kind known as 

 optical, and as the long fronds sway gently in the water, 

 its living jewels glow blue or green according as the light 

 touches them at one angle or another. When first seen 

 under favourable conditions this is one of the sights which 

 stay in the memory, for there is something in the exact 

 harmony of colour between weed and shell which seems to 

 give the blue colour an added glow. Beautiful as the 

 limpets are, however, they are not quite harmless com- 

 panions for the oar-weed, for you will find that they eat 

 very considerable holes in its fronds, in spite of their small 

 size as compared with them. Pull up a plant of Laminaria 

 by the roots, and embedded in these, in company often with 

 many other strange creatures, you will find another variety 

 of the limpet. While the first variety is a thin, delicate, 

 transparent shell, brown in colour with blue rays, the second 

 is much stouter, paler in colour, and usually without trace of 

 the blue rays. The first is the typical Helcion. pellucidum, 

 the second Helcion pellucidum var. Iccvis. The first eats 

 the fronds of the oar-weed, and so produces those torn and 

 ragged fragments which are constantly thrown on the beach ; 

 the second, by burrowing in the roots must weaken these, 

 and so assist the waves in tearing up the great plants which 

 appear on the shore after every storm. They usually bring 

 with them many curious and beautiful creatures, so the 

 naturalist has some reason to be grateful to the tiny limpet. 



The transparent limpet is closely related to Patella, and 

 in the absence of a true gill differs from the next two 

 limpets, Acmcea testudinalis and Acmcea virginea, which 

 both possess a delicate white branchial plume. In habitat 



