3l6 KEW : THE FACULTY OF HOIMING IN GASTROPODS. 



LIMPETS. 



In 1 83 1, Mr. F. C. Ijukis"' remarked upon the fact that the shell 

 of the limpet is found to correspond exactly with the surface upon 

 which the animal rests, and stated that if an individual be marked to 

 avoid mistake, its regular return to its place of rest might be observed. 



Mr. George Roberts, of Lyme Regis, recorded interesting obser- 

 vations in I 847+: — 



On the slope of a great cockle rock (higher greensand rock from Whitlands), 

 at the end of the Cobb, is a basin-Hke depression, which is left partly filled with 

 water. One fine day I climbed up and found in the basin and round about several 

 small and a few middle-sized limpets. Above the level of the water (the basin) 

 was a smooth place from which a limpet had not long before moved, as the spot 

 was different in colour to the rock around ; the shape was singular. Looking into 

 the water, I saw several limpets there, and a good many little fceces of these 

 creatures. I was not long in spying my friend, who was from home. I found him 

 leaving the others and making his way steadily back to his habitat. I watched 

 his course ; he arrived, and I at once perceived a difficulty, which he made 

 nothing of, viz., the getting adjusted. He slewed himself round, and fitted 

 a little notch which he had to a small piece of projecting quartz with wonderful 

 readiness. He was tight in a moment, ready to resist the heaviest breakers or 

 any enemy. ... I find this limpet descended daily into the little basin of 

 water, met his fellows there, and duly travelled back before the tide came in, and 

 fitted the notch to the piece of quartz as before described. 



On a smooth surface out of the stroke of the breakers, according 

 to this observer, limpets halt anywhere as their choice leads them. 



Mr. J. Clarke Hawkshaw has attended to the habits of limpets 

 on the chalk at Dover ; he observes:;: : — 



It must be of great importance Xo a limpet that, in order that it may ensure 

 a firm adherence to the rock, its shell should fit the rock accurately ; when the 

 the shell does fit the rock accurately, a small amount of muscular contraction of 

 the animal would cause the shell to adhere so firmly to a smooth surface as to be 

 practically immovable without fracture. As the shells cannot be adapted daily to 

 different forms of surface, the limpets generally return to the same places of attach- 

 ment. I am sure this is the case with many ; for I found shells perfectly adjusted 

 to the uneven surfaces of flints, the growth of the shells being in some parts 

 distorted and indented to suit inequalities in the surface of the flints. 



In one case Mr. Hawkshaw noticed a clearing made by a limpet 

 round a pedestal of flint on a sea-weed-covered block of chalk. This 

 pedestal was rather more than one inch in diameter, and it projected 

 so much that a tap from the hammer broke it off: — 



On the top of the smooth fractured surface of this flint the occupant of the 

 clearing had taken up its abode. The shell was closely adapted to the uneven 



* ' Remarks on the locomotion and habits of the Limpet," ' Loudon's Mag, 

 Nat. Hist.,' iv (1831), p. 347). 



t ' On the habits of the Limpet,' ' Ann. and Mag. Nat. Hist.,' xix (1847), 70-71. 



+ ' On the action of Limpets {Patella) in sinking pits in and abrading the surface 

 of the chalk at Dover,' ' Journ. Linn. Soc, Zool.', xiv (1879), pp. 406-411. 



Naturalist, 



