124 APPENDIX. 



and slightly lobed in front, rounded, and with a small fissure 

 behind ; branchiae formed of an elongate, tapering, conical pro- 

 cess, provided on each side with a series of spirally twisted 

 lamin?e, placed opposite each other ; on the posterior portion 

 of the right side is a produced branchial filament. — Eggs of V. 

 cristata, f. 38 ; eggs of V. obtusa, f. 55. 



Genus V— LYMN^EA. 



Lymn^a stagnalis, pi. XXIV, f. 44. 



Animal with a short, broad foot ; tentacles short, broad, and 

 compressed, eyes situate near the outer side of their base, 

 destitute of auricles at their base ; body large, central, and 

 spiral; mantle with a simple margin. — Eggs of L. ovata, f. 31; 

 32 ; eggs of L. peregra, f. 4 1 , 42, 43. 



Genus VI.— AMPHIPEPLEA. 



Animal closely resembling that of (he genus Lymna?a, but 

 having a lobed produced edge to its mantle, so as to cover the 

 shell. 



Genus VII.— PHYSA. 



Physa hypnorum, pi. XXIV, f. 27. 



Animal with the foot elongated, with the spiral body placed 

 in its centre; mantle large, with a lobed margin, expanded over 

 the shell — Eggs of P . fontinalis, f. 33. 



Genus VIII._PLAN0RBIS. 



Planorbis corneus, pi. XXIV, f. 26. 



Animal with a small foot ; body long, slender, and subcen- 

 tral ; tentacles with an auricle at the base ; neck with three 

 orifices on its left side. — Eggs of P. corneus, f. 34 ; eggs of P. 

 contortus, f. 29, 30. 



Genus X.— CYCLOSTOMA. 



Cyclostoma elegans, pi. XXIV, f. 24. 



Animal with the foot broad, formed of two longitudinal por- 

 tions ; body central and spiral, enveloped in a mantle, with a 

 simple margin. 



