190 



NOTES. 



On tkio Extension of the Distribution of the American 

 Slipper- Limpet {Cjiepidula fornigata) in the English Coastal 

 Waters. {Read \oth Noremher, 1914.) — The introduction and early 

 spread of the American Slipper-Limpet on the Essex coast since about 

 the year 1880 has already been described by Orton,^ and later by 

 Murie." It is now of interest to record the progress of the invasion of 

 English waters by this animal. 



I have been informed by Mr. W. R. Butterfield, Curator of the 

 Hastings Museum, that a few specimens of Crepidula have been taken in 

 the Hastings locality, chiefly on shells of the common whelk, Buccinum 

 U7idatum, from about the year 1908 or 1909.^ Now it is well known that 

 the tidal streams of the English Channel meet and separate in the 

 Hastings district, thus this region forms an excellent new centre of 

 distribution for the further spread of the invading limpet by means of its 

 free-swimming larva). So far, however, there appear to be only three 

 additional localities in the English Channel where Crepidula is known 

 to occur. 



At the request of Mr. G. C. Robson of the British Museum, 

 Miss Florence Jewell in May, 1913, kindly sent me a living specimen of 

 Crepidula fornicata, which was obtained from the harbour at Emsworth 

 in Hampshire during the same month. This specimen was the smallest 

 of a chain of four individuals, the largest of which then measured about 

 1§ inches long. Subsequently fishermen have brought in to Miss Jewell 

 on five separate occasions fourteen other specimens from the same 

 district. In Sussex, at Selsey Bill and Shoreham, Mr. Ronald Wi nek worth 

 of Brighton has been good enough to inform me that he has found a fresh 

 specimen in the former locality in December, 1911, and a living one in the 

 latter, about March, 1912, at low-water mark, discoveries which no doubt 

 indicate the presence of greater numbers of this animal in the neigh- 

 bouring deeper waters. Thus there can be no doubt that the slipper- 

 limpet is gradiia,lly extending its distribution westwards down the 

 English Channel. It has undoubtedly effected a highly successful 

 invasion of the English coastal waters,* for it is now to be found at 

 various places between ]\Iersea Island on the coast of Essex — in which 

 region it was first introduced — to Emsworth in Hampshire. Crepidula 

 therefore furnishes an excellent example of the efi&cacy of a free-swimming 



^ J. H. Orton, " On the Occurrence of Protandric Hermaphroditism in 

 Crepidula fornicata ^^ : Proc. Roy. Soc, vol. Ixxxi, B, pp. 468-84, text- 

 figs., 1909. 



^ J. Murie, " ' SHpper Limpet' or 'Boat Shell', Crepidula fornicata: its 

 Introduction and Influence on Kent and Essex Oyster Beds" : Zoologist, 

 No. 84-5, November 15, 1911, pp. 401-15, pis. vi, vii. 



' See also W. Ruskin Butterfield, Handbook to Collections in the Corporation 

 Museum, Hastings, 1911, p. 36. 



■* I have obtained this year from the Essex coast chains of from two to 

 nineteen individuals, whereas in 1909 the largest chain met with contained 

 only thirteen individuals. This fact indicates that Crepidula had not 

 attained a maximum of virility in 1909, and has since continued to extend 

 its influence in these excellent feeding-grounds. Whether it has yet 

 reached its maximum of development is still doubtful. 



