S72 Mr Forbes's Physical Notices of' the Bay of Naples, 



pillars of African marble, now lying on their sides, have also 

 suffered from their attacks ; but the granite pillars are untouch- 

 ed. Ferber, with that inaccuracy which in the course of these 

 papers we have so often noticed in his work, asserts, apparent- 

 ly at a venture, that the Pholades only work at the surface of 

 the water *, a position completely overthrown by Spallanzani, 

 who has seldom or never found them on the Italian coast at 

 the surface, but had them fished from all depths, down to that 

 of 142 feet. They work, however, where the tides are consi- 

 derable, even in rocks uncovered at low water, as in those at Jop- 

 pa, in Mid-Lothian, of which Mr Stark has given an account, 

 and which I have myself examined. At present, the Mytilus 

 lithophagits is not found in perfection in the Bay of Baja, 

 though Pini found some small specimens of a similar species 

 in the piers of the ancient mole commonly called that of 

 Caligula. This, however, need not surprise us, or render the 

 occurrence of these shells in the pillars of the temple more unac- 

 countable, for animals of this description are migratory in their 

 habits, of which we have an example given by Pennant,*!* 

 who states that these genera abandoned Livonia and Curlan- 

 dia in 1313, and subsequently the shores of the Baltic, but 

 reappeared abundantly in 1713. A partial desertion of the 

 coast need not therefore surprise us ; and a foreign traveller 

 who has attended to the conchology of this part of Italy, gives 

 Naples as a habitat of the " Mytilus lithophagus^'' and especi- 

 ally the coast of Taranto, where they are used as an article of 

 food. X The Pholas dactylus of Linnaeus occurs in the same 



* Ferber's Travels, p. 179. 



+ Arctic Zoology. Since writing the above, the following ingenious re- 

 mark, confirmatory of the theory supported in the sequel of this paper, 

 has been communicated to me by a gentleman well versed in zoology. 

 " The migrations of boring testaceous mollusca which burrow in submerg- 

 ed wood as well as calcareous rocks, are easily accounted for by means of 

 tirift-wood, &c. But if the sea, by some convulsion of nature, had very 

 suddenly receded from the location of the Mytili and Pholades in the Bay 

 of Baja, the reason of their having afterwards ceased to multiply in that 

 place is apparent from the instant destruction of the colony. If, on the con- 

 trary, the sea had gradually receded, the presumption is, supposing the 

 submerged rocks of a nature to afford them a retreat, and all things else 

 the same, that they should still be found alive at that locality." 



X Ulysses* Travels in Naples, 1789- Translated by Aufrcre. Appen- 

 dix, p. 498. 



