8o 



NOTE ON THE OCCURRENCE OF FRESH- 

 WATER MOLLUSCA IN A WATER-MAIN 

 AT POPLAR. 



By A. S. KENNARD and B. B. WOODWARD, F.L.S., F.G.S. 

 [Read April d^th, 1903.] 



IT has long been known that fresh water mollusca are able to 

 accommodate themselves to the artificial conditions of 

 underground water-pipes, but hitherto only three species, 

 Dreissensia polymovpha (Pall.), Nevitina fluviatilis (Linn.), 

 and a Limnoca have been recorded.^ Of these the first-named has 

 been found in London, Manchester, and Birmingham, while the 

 two latter occurred in London. Recently Dr. Frank Corner, F.G.S., 

 forwarded to us some material which had been obtained from a 

 disused iron water-main in Poplar. On examining it we were 

 able to identify no less than eleven species of mollusca: — 



Ancylns fluviatilis, Miill. 



Velletia lacustvis (Linn.) 



LimncBa pevegev (Miill.) 



Planorhis crista (Linn.) 

 „ alhus, Miill. 



Neritina fluviatilis (Linn.) 



Bithynia tentacnlata (Linn.) 

 „ leachii (Shepp). 



Dreissensia polymorpha (Pall.) 



Sphceviuni corneum (Linn.) 



Pisidium subtnmcatum, Malm. 

 From the numbers there can be no doubt that these species 

 had thoroughly established themselves in such apparently 

 uncongenial surroundings. The most abundant form was 

 Dreissensia polymorpha, but none of the examples attained to a 

 large size, 27 mm. being the length of the largest valve, but this 

 is apparently owing to the crowded manner in v/hich they lived. 

 The next most abundant form was Planorhis crista {= nautileus), 

 which occurred of all ages, and was well-developed, some 

 examples measuring 3 mm. in diameter. P. alhus also was by no 

 means dwarfed, the largest specimen attaining a diameter of 

 5 mm. 



I Jeifreys (J. G.) British Conchology (1862). Vol. i, p. 48). 

 Standen (R.), Naturalist, 1887, pp. 159-160. 

 Macgillivray (J.), Zoologist, 1852. Vol. x., p. 3.420. 



