284 CONCHIFERA. 



Cyclas fontinalis. Nilson, 101.; Drop. 130. t. 



10. f. 8. 11. 



Cyclas gibba. Alder, Cat. 41. 

 Euglesa Henslowiana. Leach, MSS. Brit. Mus. 

 Pisidium pusillum. Jenyns, Monog. 14. t. 20. f. 4. 6. 

 Inhab. ponds. 



* * Shell inequilateral. 



118.4. PISIDIUM pulchellum. Beautiful Pera. (t. 12. 

 f. 151.) Shell oblique-ovate, ventricose, deeply 

 striated ; umbones rather blunt, simple. 



Pisidium pulchellum. Jenyns, Monog. 18. t 21. f. 1. 



Cardium amnicum Jun. Montag. T. B. 88. 



Var. 1. Smaller; shell thin, finely striated, um- 

 bones rather acute. 



Pera pulchella. Leach, MSS. Cab. Brit. Mus. 



Pisidium fontinale. Pfeiffer. 



Cyclas fontinalis. Brown, Edin. Journ. N. 8f G. 

 Soc. i. 11. t. 11. f. 5. 7. ; Alder, Cat. 41. 



Pisidium pulchellum @. Jenyns, Man. 1. c. t. 2 1 . f. 2, 3. 



Var. 2. Shell obliquely oval, finely striated, com- 

 pressed, margin acute. 



Pisidium pulchellum 7. Jenyns, Mon. 18. 



Var. 3. Shell rather oblong, very ventricose, deeply 

 striated; edge very blunt, hinge margin nearly 

 straight. 



Pisidium pulchellum 8. Jenyns, Mon. 18. t. 21. 

 f. 4, 5. 



Inhab. ponds, Birkham Common, Surrey. 



Animal white; siphon variable, conical or elon- 

 gate, with an entire or lobed end. 



The siphonal tube assumes a variety of appearances 

 even in the same individual, and it is very interest- 



