240 ON PETRICOLA PHOLADIFORMIS. 
NOTE XU 
PETRICOLA PHOLADIFORMIS LAM. 
ON THE DUTCH COAST 
BY 
Dr. J. H. VERNHOUT. 
(With a sketch of the Dutch coast). 
In 1907 Mr. Caesar R. Boettger') called attention to 
the fact that this species, an inhabitant of the North- 
American seas, since the last decennium of past century 
is spreading on the European coast. In Europe it was 
found first in England at Cricksea on the river Crouch, in 
July 18907), and on the Lincolnshire coast ®). The following 
years brought further references about the occurrence of 
Petricola pholadiformis on the English coast*). At present 
the localities where it is found, stretch from Shellness, near 
Sandwich, Kent, in the south, to Mablethorpe, Lincolnshire, 
in the north. Mr. Loppens®) was the first to notice this 
species on the continent; he found it near Nieuwpoort on 
the coast of Belgium, in 1899. Very soon afterwards other 
localities were known where Petricola pholadiformis occurred 
1) Caesar R. Boettger. Nachrichtsbl. der Deutschen Malakozool. Ges. 1907, 
39. Jahrg. p. 206. 
2) W. Crouch. Ordinary meeting of the Malacol. Soc. of London, 8th May 
1896: Proc. Mal. Soc. 1897, Vol. II, p. 134. 
3) A. S. Kennard. Proc. Mal. Soc. 1909, Vol. VIII, p. 3. 
4) J. E. Cooper. Ordinary meeting of the Malacol. Soc. of London, 12th July 
1895: Proc. Mal. Soc. 1895, Vol. I. p. 291. 
J. E. Cooper and A. S. Kennard. Ordinary meeting of the Malacol. Soc. 
of London, 8th May 1896: Proc. Mal. Soc. 1897, Vol. II, pp. 134, 135. 
A. S. Kennard. Loe. cit. sub *). 
5) K. Loppens. Annales Soc. royale Zool. et Malacol. de Belgique, 1902, 
Tome XXXVII, pp. XLI, XLII. 
Notes from the Leyden Museum, Vol. XXXIV. 
