270 MARINE ZOOLOGY OF ARRAN. 



detection, whatever it may regard as palatable to its taste or 

 requisite for its necessities. Both the Pleurobranchus and 

 the Aplysia may be procured from pools at the north end of 

 Holy Island. At Lamlash, in the neighbourhood of the old 

 quay, the blocks of sandstone, which lie scattered in all direc- 

 tions, contain here and there good specimens of one of the 

 borers a division of the mollusca, whose habit is to penetrate 

 either sand as the common cockle, Cardium edule or wood, 

 as the different species of Teredo or stone, as the genus 

 Phola*, a bivalve, of which the shell in some species is ex- 

 tremely fragile, and although wonderfully well adapted to 

 its work as an excavator of solid rocks, requires the utmost 

 caution when being handled in our collections. The species 

 that bores through the sandstones at Lamlash is Pholas 

 crispata. The wood-borer, Teredo navalis, is common in 

 many parts of the Clyde, as may be proved by witnessing its 

 destructive operations at Ardrossan and Fairlie, on the Ayr- 

 shire side, where also its ally, Xylophaga dorsodis, has done 

 its full share of mischief Another species, less common, 

 and of larger growth formerly unknown, as is supposed, 

 higher up the Clyde than Port- Patrick namely, Teredo Nor- 

 vegica introduced itself into Lamlash Bay, and, during the 

 short period of about seven years, it had almost demolished 

 the massive supports of the pier a commodious and sub- 

 stantial landing-place, erected, as the owner undoubtedly 

 thought, for the convenience of himself and friends. The 

 Teredo, however, commenced and continued its operations 

 unnoticed not oae pile of the water-covered timber escaped 

 the whole was pierced in lengths varying from a few inches 

 to about two feet, when, in the hurricane of February, 1856, 

 a vessel was driven upon the spot, and almost the entire 

 structure was swept away.* On an examination of the frag- 

 ments thrown upon the island, several specimens of the cal- 

 careous tube, formed by the animal in the course of its pro- 



* This pier was built by the late Mr. Oswald, member for the city 

 of Glasgow. 



