found on the Sea-coast near Edinburgh. 431 



next professes to give an account of the manner in which the 

 Pholades perforate their dwellings ; but, from the contrariety 

 of his statements, and his completely misunderstanding one of 

 the authors quoted by himself, little reliance is to be placed upon 

 his authority as an observer. In one passage of his Zoomorphose, 

 when describing the shell of the Pholas dactylus, he says it resem- 

 bles a file, with elevated strias and asperities, dentated and crowd- 

 ed from the top of the shell to its base, -in such a manner that the 

 strongest points are towards the head. " It appears," says he, " that 

 with these arms it pierces the stones, and enlarges its tomb as it 

 increases in size." But, in a passage a little afterwards, he adds, 

 with a strange forgetfulness of what he had previously writ- 

 ten, " In proportion as this animal grows, it digs its hole with a 

 round and fleshy part like a tongue ; and it is not with its two 

 valves, nor with its teeth, that it performs this operation." Fur- 

 ther on he remarks upon another species, that it " is armed 

 at its extremity with two strong and cutting points, in form of 

 an auger, of which the dentated contour gives it the means of 

 turning upon itself, and of piercing the stone downwards. The 

 stria? and the teeth do the rest *." 



Among the more modern writers, PENNANT mentions having 

 frequently taken the Pholades " out of the cells they had form- 

 ed in hard clay, below high water-mark, on many of our shores. 

 They also perforate the hardest oak-plank that is lodged in the 

 water. The bottoms of the cells," adds this acute observer, " are 

 round, and appear as if nicely turned with some instrument f ." 

 MONTAGU, speaking of the Mya Pholadia, says, " It is probable 

 this, as well as similar animals whose habits are to perforate 

 stone, are provided with an acid, or some other solvent men- 



* L'Hist. Nat. eclaircie dans une de ses parties principales. Zoomorphose, p. 69, 

 70. Paris, 1757. 



t British Zoology, vol. iv. p. 158. 



VOL. x. P. ii. 3 i 



