CENSUS. 105 



A. anatina (L.). 



Eng. S. 6 13 15-16 2022 27 32 34 38 40. Wales 

 45. Eng. N. 5567. Scot. 83. No records for Ireland, 

 Dreissensia polymorpha (Pall.). 



Eng.S.36i72i 242931 3436 40. Eng.N.55 59 

 63-64. Scot. 76-77 83 86. No records for Wales or Ireland. 

 Neritina fluviatilis (L.). 



Eng. S. 13-469 ii 13-14 16 18-19 21 24 27 29 33 

 37 39. Eng. N. 53 5557 6065. Scot. 76 in. Irel. 

 124 131-132 136 138 142. No records for Wales. 

 Vivipara contecta (Millet). 



Eng. S. ii 17 2225 2729 31-32. Eng. N. 5356 

 5864. No records for Wales, Scotland or Ireland. 

 V. vivipara (L.). 



Eng. S. 13 16 18 20 23 25 27 31 40. Wales 47. 

 Eng. N. 53 55 59 61 64. No records for Scotland or 

 Ireland. 

 Bythinia tentaculata (L.). 



Eng. S. i 37 913 1525 2734 37 40. Wales 

 41-42 47. Eng. N. 5367 70. Scot. 76-77 83. Irel. 113 

 115 U7 I2 !23 I2 4 127 131-132 135-136 138 142 144. 



B. leachii (Shepp.). 



Eng. S. 5-6 ii 1416 1923 25 2729 3234 

 38 40. Wales 45. Eng. N. 53 57 59 64. No records 

 for Scotland or Ireland. 

 Valvata piscinalis (Miill.). 



Eng. S. i 3 6 913 1529 3234 36 3840. Wales 

 41 45 47 52. Eng. N. 5367 6971. Scot. 73 76 80 83 

 8 5~ 9 Ir- el. 114 n8 123 131-132 136 138-139 142144. 

 V. cristata Miill. 



Eng. S. 6 ii 19 21 23 25 27-28 31-32. Wales 

 41-42 45 47 52. Eng. N. 54 5664 66-67. Scot. 73 77 

 80 85 90. Irel. 131-132 138 144. 

 Segmentina nitida Mull. 



Eng. S. 14 17 21 23 27 29 37. Wales 47. Eng. 

 N. 54 59 61 64. No records for Scotland or Ireland. 

 Planorbis nautileus (L.). 



png. S. 1369 1114 16 19 21 23 27-28 30 32 3740, 



