KEW : THE FACULTY OF HOMING IN GASTROPODS. 317 



surface, which it would only fit in one jiosition. The cleared surface was in a 

 hollow, with several small natural cavities, where the limpet could have found 

 a pit ready made to shelter in ; yet it preferred, after each excursion, to climb up 

 on to the top of the flint, the most exposed point in all its domain. 



The area of rock-surface which one limpet keeps clear of all but 

 the youngest growth of sea-weed varies, according to Mr. Hawkshaw, 

 from 8 to 14 square inches. 



In 1883, Mr. David Robertson made a number of observations 

 on the habits of the limpet, of which an account was published in 

 18S5.* To ascertain the movements of the limpet in its natural 

 haunts an iron arch was placed over the animal ; a wire, let 

 down through the arch, rested on the crown of the shell, so 

 that when the animal left its place, the wire dropped on the rock. 

 Observations were regularly carried on from the 21st of June till 

 the 20th of August, and were made on different limpets and 

 on different zones of the tidal belt. Near high-water mark the rocks 

 were frequently covered with young balani, which surrounded the 

 limpets closely. There was always a little bare space on one or 

 other side of the animals, beyond which they were not seen to 

 wander. In these cases the animal, after feeding, was always found 

 close to the drop wire, as if endeavouring to get back to the exact 

 spot it had left. Further down, where the rocks were smooth and 

 clean, it was occasionally found that the limpets settled down a few 

 inches from the spot which they had left, and again by another tide 

 or two were back on their old site. A series of careful observations 

 were made on a limpet kept in a glass jar, 6 inches deep and 9 inches 

 in diameter. By means of thin wires let down through the perforated 

 zinc with which the jar was covered, and of a gummed ticket placed 

 on the outside of the glass, the position of the limpet from time to 

 time could be registered. 



I found that it would return once or twice to the same spot, then change to 

 another, then return back again to where it had been at first. Sometimes it would 

 settle on the exact spot it had left five or six days before, and once as far back as 

 thirteen days. Generally it settled on the exact spot it had formerly occupied, yet 

 occasionally it would be a little to the one side or the other. In most cases it 

 came down on the site from above, and occasionally rested a little before it finally 

 reached it. 



Observations on this subject have also been made by Mr. J. R. 

 Davis at theScottish Marine Station, Granton, Edinburgh. t A number 

 of limpets were marked with white paint, and corresponding marks 

 made near their scars. The greatest distance from its scar at which 

 a marked limpet was seen was about three feet. This distance, 



* 'Notes on the Common Limpet,' Trans. Nat. Hist. Soc. Glasgow (n.s.), 

 i(i885), p. 9-21. 



t ' The habits of the Limpet,' ' Nature,'' xxxi (1SS5), pp. 200-201. 

 Oct. 1890. 



