192 HIGHWATER MARK. 



res angustce domi, the greater part of his dwelling re- 

 mains a terra incognita to him ; for, when we drag 

 him from his foot-hold, we find that he has really 

 lived in a cavity commensurate (and no more) with 

 the outline of his body ; as if the substance of the liv- 

 ing wall had gradually grown around him since he 

 first set foot there, just as the soil of London has 

 risen around the site of the ancient St Paul's. 



And so it has, doubtless. Even though a more 

 intimate acquaintance with our eremite's manner of 

 life should induce us to reject the supposition of his 

 actual immobility, there can be no question that 

 this cavity is fashioned on the animal's body, partly 

 by a slow erosion of the surface, and partly by the 

 growth of the plant. And yet he may occasionally, 

 nay, frequently and periodically, wander. Some 

 curious passages in the history of his bigger brother, 

 the common rock-limpet, may help us to a little 

 light on the matter. We often find this familiar 

 species imbedded in a shallow, but very perceptible 

 and well-defined, depression excavated out of the solid 

 rock, shale, or limestone, or whatever else it may 

 chance to be ; but this cavity in every case so accu- 

 rately fitting the dimensions of the animal, as to 

 leave no room for doubt that the former has been 

 really modelled by the latter. Now the limpets are 

 all exclusively vegetarians in their diet; and the 

 problem was to understand how the creature could 

 procure his daily dinner of greens, while yet he was 

 so manifestly a fixture. But a peering naturalist, 



