PHOLAS 



these the P. crispata, JDactylus, Candida and parva are the 

 most common ; several others are described hy Turton in 

 his British bivalves^ of which we are quite convinced the 

 P. lamellata is only the young of P. papyracea; we are not 

 acquainted with his P. tuberculata. Among the species of 

 this interesting Genus that are not found on our coasts 

 are the P,] orientalis, a very scarce East Indian species, 

 and the P. costata, of which we have drawn a fine Speci- 

 men brought from Mexico by Mr. Bullock, for the use of 

 which we are indebted to the kindness of the Rev. Dr. 

 Goodall. Much confusion appears to prevail in regard to 

 several very distinct species: among these we believe the 

 papyracea of Turton is the 5^na^« of Montagu • the clavata 

 of Lamarck is the striata of Linneus, but not of Mont. 

 We cannot approve of Lamarck's changing the name of 

 Montagu's P. parva to P. dactyloides. 



Fossil Pholades are rare, they occur in the Calcaire 

 grassier and contemporaneous formations in several places, 

 and also in our Crag : several very interesting species are 

 found in Italy and in Touraine, as well as in the vicinity 

 of Paris, where these and several other perforating shells 

 have been discovered in a fossil state in the cavities 

 which they have themselves formed. 



The manner in which these and other perforating 

 shells produce the cavities in which they live, in stone, 

 wood, &c. has long been a subject of controversy j we are 

 the less inclined to add ourselves to the number of dis- 

 putants, as we understand the subject has lately under- 

 gone experimental investigation, and that the results are 

 likely soon to be made known; we would only state that 

 it cannot be by a rotatory motion, since the cavities are 

 fitted to the shape of the shell; and since animals whose 

 shells are perfectly smooth on their outside are equally 

 capable of producing these cavities as others whose ex- 

 ternal surfaces are rough like a file ; nor do we think it 

 can be by the chemical action of any solvent, since the 

 same effect is produced on Wood, Limestone smd /Sand- 

 stone. We have been informed that the Teredo eats its 

 way into wood ; query, do the Pholas, and others per- 

 forate JVood, Chalk, Limestone and even Sandstone in the 

 same manner? or have some of them the power of dis- 

 solving stone, while others form their cavities by eatip^ 

 away wood. 



