12 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



After sailing down from the port of Bangor, taking 

 surface gatherings on the way, we reached the island in 

 good time for the evening low tide, and spent the hours 

 till dark collecting amongst the reefs and boulders of the 

 South Spit. One of the first objects found on the shore 

 was a rather interesting specimen. It was an example 

 of the common limpet (Patella vulgata) , which, in place 

 of being attached to a rock, was sticking firmly to the 

 rounded surface of a piece of iron bar from a wreck. The 

 limpet was moulded to the surface. Its lower part was 

 strongly concave, and the edge of the shell was curved up 

 in the middle on each side, and down at each end, so as to 

 be able to embrace about half the circumference of the 

 cylindrical bar. The animal had evidently grown so as to 

 stick closely and tightly to the surface. Now, this would 

 not be at all surprising in a coral or an ascidian, or any 

 animal which remained adhering to one spot all its adult 

 life ; but it is remarkable in a case like the limpet, which, 

 it is generally supposed, does not remain rooted to one 

 spot, but wanders about in search of food. 



Although when we notice limpets on rocks between 

 tide marks they are generally fixed and motionless, still 

 Prof. J. R. A. Davis has shown that they can loosen their 

 hold and crawl over the rocks for some distance. It is 

 noticed, however, that when the rock is not very hard, as, 

 for example, in the case of the limestone blocks at Puffin 

 Island, each limpet occupies a well-marked depression 

 exactly its own shape. From this it is clear that the 

 animals are not on mere temporary resting places, but 

 are in their own "roosts" or homes, to which, if they 

 leave them, they return regularly, and which they have 

 themselves excavated to a considerable depth and with 

 the precise shape of the outline of their own shells. 

 So much so that they have to place themselves with the 



