22 
BRITISH MOLLUSCA. 
Pera appendiculata, Leach , MSS. Brit. Mus. 1819. 
Cyclas appendiculata, Turton , Man. ed. 1. t. 15. f. 6; Hanley, 
Rec. Shells, i. 91, Supp. t. 14. f. 42. 
Pisidium Henslowianum, Jenyns, Mon. 20. t. 21 . f. 6, 7, 8 , 9 ; 
Gray, Man. L. fy F. W. Shells, 285. t. 1. f. 6 ; Brown, III. Con. 
G. B. 95. t. 39. f. 25; Forbes 8c Hanley, Brit. Moll. ii. 131. 
t. 37. f. 11. 
Pisidium acutum, Pfeiffer, Wiegm. Arch. 1831, pt. i. 230. 
a — n. Cambridge. Presented by Rev. J. S. Plensiow. 
o — t. York. Presented by P. Carpenter, Esq. 
u — c c. Preston. 
6. PlSUM AMNICUM. 
Tellina amnica, Muller, ii. 205; Linn. Trans, viii. 60; Dillwyn, 
Rec. Shells, i. 105 ; Don. Cat. 31. t. 7- f. 2 a; Turt. Diet. 168; 
Wood, Gen. Conch. 153. t. 47. f. 6 ; Ind. Test. t. 3, Tellina, 
f. 19 ; Penn. B. Z. ed. 1812. iv. 185. no. 24. 
Tellina rivalis, Maton, Linn. Trans, iii. 44. t. 13. f. 37, 38 ; Don. 
B. T. t. 64. f. 2. 
Cardium amnicum, Montag. T. B. 86. 
Cyclas palustris, Drap. 131. t. 10. f. 15, 16 ; Gras, Moll. t. etfl. 
France , 73. t. 6. f. 6. 
C. obliqua, Lamk. Hist. v. 559, ed. 2. vi. 269 ; Nilsson, 99; Kickx, 
Moll. Brab. 89. 
Pisidium obliquum, Pfeiffer, 124. t. 5. f. 19, 20 ; Brown, III. Con. 
G. B. 94. t. 39. f. 22 ; Philippi, Moll. Sic. ii. 31. 
Cyclas amnica, Turt. Biv. 250. t. 11. f. 15 ; Man. ed. 1. 15. f. 5 ; 
Fleming, B. A. 453 ; Hanley, Rec. Shells, i. 89. t. 3. f. 19. 
Pisidium amnicum, Jenyns, Mon. 21. t. 21. f. 2 ; Forbes fy Hanley, 
Brit. Moll. ii. 133. t. 37. f. 8, 9. t. O. f. 8, animal. 
Young shell ratber compressed ; umbones scarcely prominent. 
Var. 1. Shell with very deep grooves. 
Pera iluviatilis, Leach, MSS. in Brit. Mus. 
Pisidium amnicum /3, Jenyns, Mon. 22. 
Var. 2. Shell nearly smooth with slighter striae. 
Pera Henslowiana, Leach, MSS. Brit. Mus. 
Pisidium amnicum y, Jenyns , Mon. 22. 
a—ff. Bexley, Kent. 
g g — o o. Coggeshall, Essex. 
p p — w w w. Cambridge. Presented by Rev. J. S. Henslow. 
Pera Henslowiana, Leach, B. M. 
x x x — a a a a. York. Presented by P. Carpenter, Esq. 
bbb b — n nnn. Britain. 
Pisidium obliquum, Brown. 
