242 ON PETRICOLA PHOLADIFORMIS. 
Petten, 1908, Mr. K. W. Dammerman. 
den Helder, 1907. 
Coast of Texel, 1908, Mr. K. W. Dammerman; 1909, 
Mr. W. C. van Heurn. 
Coast of Vlieland, 1906, Mr. W. C. van Heurn. 
Sketch of the Dutch coast. 
From these facts, one can conclude that Petricola 
pholadiformis will be found on all points of our coast; 
thus it has a nearly uninterrupted distribution from Dun- 
kerque to Fanö. 
I can affirm the statements of Mr. Giard') and of Mr. 
Pelseneer?), who suppose that on the Belgian coast Petricola 
pholadiformis is on the way to supplant Pholas candida 
L. This autumn (Sept. 1912)1 found at Domburg only 
Petricola pholadiformis, no Pholas candida, which latter 
species I recollect having found there in great abundance 
many years ago. 
Leyden Museum, 224 October 1912. 
1) A. Giard. Feuille des jeunes Naturalistes, 1907, 1Ve série, 37e année, p. 51. 
2) P. Pelseneer. Loc. cit. 
INotes from the Leyden Museum, Vol. XXXIV. 
