l86 JOURNAL OF CONCHOLOGY, VOL. 12, NO. 7, JULY, I908. 



p. 461). Canal at Trowbridge, Salisbury (Vize); Edington and 

 Amesbury (E.W.S.). 



Pomatias elegans (Miiller). — Widely distributed on the chalk. 

 In the woods at Lackham (Montagu); Roundway Hill, Salisbury 

 (Vizej; Devizes (Miss Cunnington and Heginbothom); Edington 

 and Marlborough (E.W.S.). 



var. albescens Des Moulins. — Gully on south side of Oare Hill, 

 near Marlborough (Bromehead). 



var. pallida Moquin-Tandon. — Lane on the south side of 

 Kennet, opposite Mildenhall, near Marlborough (Bromehead). 



var. ochroleuca Moquin-Tandon. — Devizes (Miss Cunnington 

 and Heginbothom). 



Acicula lineata (Draparnaud). — A rare species. Dr. Blackmore 

 found it in the brickearth at Fisherton, and the Rev. J. E. Vize on 

 roots of grass at Upavon. 



Neritina fluviatilis (Linnd). — A very local species. On stones 

 in the canal at Trowbridge, Salisbury (Vize); Dr. Maton also recorded 

 it from Salisbury; Great Bedwyn (Townsend); canal at Devizes 

 (Heginbothom). 



Dreissensia polymorpha (Pallas). — Apparently confined to the 

 Avon and Kennet Canal. Very abundant near Trowbridge in the 

 canal, and reservoirs and canal at Devizes (Vize); Devizes (Miss 

 Cunnington and Heginbothom). 



Is anything known of the introduction of this species into the 

 Kennet Canal? It is supposed to have been imported into this 

 country in or about the year 1824. Within twenty years of that date 

 it was reported from two counties in Scotland and thirteen in England. 

 It was unknown to the Rev. J. E. Vize, who contributed a list of the 

 Land and Freshwater Shells of Wilts., in 1863, to volume ix. of 

 the Wiltshire Magazine, or, at least, he makes no reference to it. In 

 the 1889 Census List of British Non-Marine MoUusca it is recorded 

 from twenty-one counties and vice-counties in England and two in 

 Scotland. In the 1902 Census it is given under twenty-five English — 

 including S. Devon, N. Somerset, Surrey and Middlesex— and four 

 Scotch. Wilts, must now be added to the list and specimens have 

 been sent to the Society's Recorder. There are no records from 

 Wales and Ireland. "The Dreissena is perhaps better fitted for dis- 

 semination by man and subsequent establishment than any other 

 freshwater shell; tenacity of life, unusually rapid propagation, the 

 faculty of becoming attached by a strong byssus to extraneous 

 substances, and the power of adapting itself to strange and altogether 

 artificial surroundings have combined to make it one of the most 

 successful molluscan colonists in the world" (H. Wallis Kew in 

 "Dispersal of Shells," p. 219). 



