276 THE FLESHY FLUSTRA. 



delicate in tlieir texture. About the wet walls were 

 scattered irregular patches of a scarlet sponge fHali- 

 chondria sanguineaj as big as one's hand, or bigger, 

 and many specimens of a smaller kind of a yellowish 

 colour, more projecting into teat-like eminences (H. 

 paniceaj. Many limpets were about, some of which 

 were very evidently stationary inhabitants, notwith- 

 standing their power of free locomotion, for the sur- 

 face of the rock on which they were seated was in 

 many cases eroded to the depth of an eighth of an 

 inch, for a space just large enough comfortably to 

 embrace the margin of the shell. Other such oval 

 depressions, from whence the limpet had either fallen 

 or wandered away, showed the spots where this little 

 shell-fish had certainly taken up his abode for a time. 

 On the roof of one of the caves I observed a 

 roundish encrusting substance of a dull olive-brown 

 colour, which attracted my curiosity, and induced me 

 to attempt its removal. I found I could easily get it 

 off by forcing the blade of my pocket-loiife under it, 

 though it adhered with considerable tenacity I after- 

 wards observed other patches of the same substance 

 in the vicinity, some of which I took away in a man- 

 ner less liable to injure its vitality, viz., by chiselling 

 off a portion of the rock itself. On examining it 

 at home, I cannot find that it disagrees with an 

 encrusting polype that is found commonly enough 

 investing the fronds of the serrated Fucus, and which 

 I presume to be the Flustra hisjnda or carnosa of 

 naturalists. It forms a rough surface, about one 

 twelfth of an inch in thickness, and spreading in all 

 directions to an indefinite breadth ; some of these 



