THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY, 



[SECOND SERIES.] 

 No. 10. OCTOBER 1848, 



XXV. — On the Boring of the Mollusca into Rocks, ^c. ; and on 

 the removal of portions of their Shells. By Albany Hancock, 

 Esq.* 



[With a Plate.] 



Few subjects in connexion with malacology have caused so 

 much discussion as the well-known excavating power possessed 

 by many of the Acephala. Numerous attempts have been made 

 to explain the manner by which these creatures work out their 

 habitations : and this matter is indeed fraught with much in- 

 terest, not merely in a philosophical point of view, but also on 

 account of its immediate relationship to the affairs of man, as 

 all persons connected with submarine works are too well aware. 

 The ravages perpetrated by some of these animals, and especially 

 by the smaller individuals of the group, the Teredines, are occa- 

 sionally of the most fearful extent, and are carried on with a 

 rapidity scarcely to be credited. 



Of the many theories advanced to explain the nature of these 

 operations, the one most generally received is, that the animal 

 works with the shell in the manner of a rasp or an auger : 

 another theory extensively believed requires a solvent ; particu- 

 larly when the burrows are in calcareous substances : and a third, 

 which has received distinguished notice, was proposed by Mr. 

 Garner in his well-known paper " On the Anatomy of the Lamel- 

 abranchiate Conchifera," published in the second volume of the 

 * Transactions of the Zoological Society / which theory accounts 

 for the phsenomenon " by the vibratile action of the parts exciting 

 constant currents of water against the substance, aided by its 

 impetus when drawn in down the elongated body of the animal ; 

 and in some cases, perhaps, by the rasping of the valves." 



In a short notice published in the ' Annals of Natural History,' 



* Read at the Meeting of the British Association held at Swansea, Au- 

 gust 9th, 1848, and communicated by the Author. 



Ann. ^ Mag. N. Hist. Ser. 2. Vol. ii. 16 



