Mollusca of Great Britain. 391 



2. Lacustris. 



Animal nigrescens. Tentacula breviora. 

 Testa .oblonga, subdepressa, vertice excentrico ; fragilis, 

 membranacea, concentric^ substriata, nigrescens. 

 Apertura oblonga. 



Long. 0.1. — Diam. 0.35. 

 Ancylus lacustris. Miill. Verm. 2. p. 199- Drop. Hist. 



des Moll. p. 47. t. 2. f. 25—27. 

 Patella oblonga. Light/, in Phil. Trans. 76. p. 168. 

 t. 3./. 1—5. 



lacustris. Gmel. Syst. Nat. 1. p. 3710. Mont. 



Test. Brit. p. 484. 



On water-plants in ditches, lakes, &c.; though rather a 

 local species. It is not uncommon in Blackpill marsh near 

 Swansea, mixed with the Planorbis nitidus. 



ADDITIONS AND CORRECTIONS. 



Page 324,ybr Cianella, read Cionella. 



Helix fusca, p. 330. 



Animal lutescenti-griseum, dorso flavescenti. Tentacula 

 praelonga, flexilia. 



Since writing the above list, I have discovered this local 

 species in great abundance in moist parts of Penllergare 

 wood, near Swansea, on the leaves and stems of the Hera- 

 cleum Sphondylium and other plants. 



Helix nitida, p. 339- 



The variety /3. is found not uncommonly under leaves, 

 decaying Boleti, <^c. in the woods at Penllergare. 

 VOL. XVI. . 3e Limneus 



