284 JOURNAL OF CONcttOLOGY, VOL. lO, NO. $, JANUARY, I903. 



Helix rotundata Mull. m. sinistrorsum at Castleton, Derbyshire.— On 



Whit-l\Ionday, whilst collecting mollusca in the Winnatts, Castleton, Derbyshire, I 

 had the good fortune to find a living reversed specimen of Hdix rotundata. The 

 typical form occurs in great numbers throughout the district, under the pieces of 

 limestone lying about on the roads and lanes, and it was under one of these stones 

 that 1 found this sinistral specimen. I have also taken a couple of the var. alba in 

 the same district. It is surprising that, considering the vast numbers of this species 

 throughout Europe, so few sinistral examples have been found. Mr. J. W. Taylor 

 tells me that the only other records are : one specimen found by Canon Lett at 

 Loughbrickland, Co. Down ; another found by Mr. Alfred Sich in his garden at 

 Chiswick ; and a fossil specimen found by Dr. Loretz in tufaceous limestone in 

 Coburg. In Adams' "Land and Freshwater Shells," 1896, both sinistral and 

 scalaiiform examples of this species are classed under the head of "deformities." 

 That a scalariform shell is a deformity I readily admit, but I fail to see how it 

 applies to a sinistral one. In my reversed specimen the animal is also reversed, 

 the openings of the generative and alimentary systems being on the left side and 

 not on the right as is usual. In those genera which are normally sinistral, e.g., 

 Clausilia, Ariophanta, Draparnaldi, etc., we do not consider them deformities any 

 more than AchalineHa, Ainphidrouius, etc., where, in some species, the proportion 

 of sinistral and dextral individuals is about equal. Then, again, take Neptunea 

 antiqiia, rarely found other than dextral now, yet whose Red Crag ancestors were all 

 sinistral — but surely not deformities! Personally, I do not like the term "mon- 

 strosity " either, as applied to reversed shells ; it would be better to say " form." — 

 JOHN W. JACKSON {Read before the Society, June 11, 1902). 



Paludestrina jenkinsi near Eastbourne. — On September 5th I paid a visit 

 to a ditch at Litlington, a few miles out of Eastbourne, where last year I had taken 

 some especially fine Valvata piscinalis and its beautiful albino variety. This year 1 

 found the ditch literally 'taken over' by Paliitestrina jenkinsi. Conchologists 

 acquainted with this species in its native haunts will know what I mean by 'taken 

 over.' They line the sides of the ditch in myriads, though I did not observe a single 

 specimen there last year. The Valvata I found dead on the mud at the bottom, 

 or attached to caddis-cases. Next day I turned the couple of hundred Paludestrina 

 that I brought away with me out of my jar of water into a shallow oblong dish of 

 water preparatory to cleaning them, and left them for about half-an-hour. On my 

 return I was surprised to find that they had formed a procession and were marching 

 round the sides of the vessel just below the surface of the water, and every one going 

 the same way (from left to right) with the exception of a very few which were still 

 at the bottom of the dish in the middle. However, as soon as one of these reached 

 the side it joined the procession. There was a complete chain of them round the 

 dish, so that I could not discover which was leading. There was no fighting nor 

 jostling ; each kept a respectful distance from his neighbour. There was something 

 very fascinating in watching this slow silent march round and round, and I can 

 quite well understand how irresistible they would be if an army of millions and 

 millions of these little molluscs were to determine to take possession of a ditch. I 

 watched them for about an hour, when I had to disturb them to clean them, though 

 I should much have liked to have seen how long the march would have continued. 

 I hope to do so, however, on a future occasion. Other freshwater molluscs will often 

 travel round a vessel of water, but I think always irregularly and independently of 

 each other, while this seemed to be a regularly organised procession, either migra- 

 tory or in search of food. The shells are large and clean, the keel varying consider- 

 ably in height. It is a common species round Lewes. —Arthur G. Stubbs {Read 

 before the Society, Sept. lOth, 1902). 



