THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[SECOND SERIES.] 

 No. 35. NOVEMBER 1850. 



XXVIII. — On the Pholadidse. By Whliam Clark, Esq, 



To the Editors of the Annals of Natural History. 



Gentlemen, Norfolk Crescent, Bath, June 26, 1850. 



I BEG to lay before you descriptions of the animals of the Plio- 

 ladidcB, including the anatomies of Pholas dactylus and Teredo 

 megutara, which, with my notes on P. papxjracea and on the 

 terebrating mollusca that have already appeared in the January 

 * Annals ' for 1850, will form a complete monograph on this 

 tribe, with the exception of the animal of P. crispata, that does 

 not occur on the southern coasts, and that of Xijlophaga dorsalis, 

 which though met with alive many years ago was not then ob- 

 served. 



Pholas, Teredo, and Xylophaga constitute the British genera 

 of this family. I have just submitted the Pholades and the Te- 

 redo megotara to a rigorous examination, not only of the external 

 organs, but I have entered into detailed observations on their 

 anatomical structure. Grave errors exist in our records relative 

 to this family, both as regards the shells and the functions of the 

 soft parts. 



It is really strange that in so celebrated and ancient a genus 

 as Pholas, so often the theme of discussion, so many doubts and 

 contradictory accounts should still pi-evail respecting the hinge, 

 cartilage, ligament and adductor muscles of the animal. Though 

 there may be errors of minutiae, I think that malacologists will 

 find, in this account, some rectifications, obscure points explained, 

 a variety of new matter, and that the observations on the struc- 

 ture of P. dactylus and Teredo megotara will assist not only to 

 illustrate this family, but, mutatis mutandis, give a general view 

 of the material points of the organization of the animals of the 

 Acephala. 



Ann. ^ Mag. N, Hist. Ser. 2, Vol. vi. 21 



