JOURNAL OF CONCHOLOGY. II7 



Alterations in the Molluscan fauna of a small 

 pond. — Some twenty-three years ago I was in the habit of col- 

 lecting shells in a small pond near to the Black Hills, Leeds. 

 At that time the only molluscan forms found there were a dwarf 

 form of Sphcerium lacustre Miill., Pisidium pusillum Gmelin, 

 Planorbis nautileus Linn., and Limniza peregra Mlill. About 

 ten years ago I resumed my visits to the locality and found in 

 addition to the species already enumerated Planorbis corneus 

 Linn. These were the only species found there until this 

 Spring, when, during one of my frequent visits, I was surprised 

 to find Physa fontinalis Linn., and Planorbis vortex Linn, were 

 added to the growing list of species. Later on Planorbis carina- 

 tus Miill., Limncea stagnalis Linn., and Ancylus lacustris Linn, 

 turned up ; and during June Planorbis contortits Linn, was found 

 in this small but prolific pond. My object in writing this small 

 note is to elicit from some of your readers whether their experi- 

 ence furnishes a similar instance of additions to a fauna. I 

 have in my mind more than one case of the partial disappear- 

 ance from a locality of a species, and sometimes of the total 

 disappearance, but I know of no similar instance of so many 

 additions to the fauna of a small pond. My friends, Mr. J. W. 

 Taylor and Mr. J. Beevers, who collected with me during the 

 years i860 — 63, will bear me out that the four species first 

 named above were the only forms at that time in the pond.— 

 W. Nelson, Aug. ist, 1883. 



Bulimus obscurus var. albinos Moq. — East Sussex 

 may be added to the list of counties in which this variety occurs, 

 as enumerated by Mr. Taylor at p. 83 of this volume. Mr. S. 

 Spencer Pearce, B.A., took a specimen on a beech tree in a 

 wood at Fitchin near Eastbourne, in September, 1881, which 

 by his kindness Mr. Taylor and I have seen. — Wm. Denison 

 Roebuck, Leeds, August 3rd, 1883. 



