12 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



its native haunts, yet some facts can be ascertained 

 in this way that could not otherwise be determined. 

 In a glass vessel the action of the mouth can be 

 distinctly seen, and even heard, which it could not 

 be on its native rock, nor could the marking of the 

 teeth of the tongue on the fine filamentous algae be 

 so well observed on the rough rock as on the clear 

 glass jar. The glass jar used was six inches deep 

 and nine inches in diameter. A limpet one-and-a- 

 half inches long was placed on the bottom and 

 covered with two inches of sea-water. 



Other limpets were put into different vessels, some 

 beginning to move soon after being put in, and 

 others at intervals of longer or shorter duration ; 

 but on the whole they were found to be so similar 

 in their general movements that I have confined 

 my remarks to the behaviour of the one referred 

 to. 



During the first two days it was not seen to 

 move from the spot on which it was first placed. 

 On the third day it moved about two inches along 

 the bottom, ^vhere it remained till the afternoon^ 

 when it moved from the bottom ujd the side of the 

 jar to the edge of the T\^ater with about one-third 

 of the shell above the surface, and there settled 

 with its head downwards, as it always does Tvhen it 

 goes to rest. The edge of the water is a common 

 situation to rest on, sometimes more and sometimes 

 less of the shell being under water and occasionally 

 the whole of it. I only once saw it leave the water for 

 two or three minutes. When the animal is at rest 

 the body is a little contracted, leaving a small space 

 occupied by water between it and the shell. When 

 the animal moves to one side the water space is 

 increased on the other ; and during these move- 

 ments the neck is much elongated, and the head 

 can be turned so far round as to reach nearly half- 

 way down the side of the body. 



From the margin of the mantle light - coloured 

 retractile filaments or cirrhi of various sizes pro- 



