124 APPENDIX. 



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

 behind ; branchia3 formed of an elongate, tapering, conical pro- 

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

 lamina), 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. ohtusa, f. 55. 



Genus V.— LYMN^A. 



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. 41, 42, 43. 



Genus VI.— AMPHIPEPLEA. 



Animal closely resembling that of the genus Lymnsea, 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.— PLANORBIS. 



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. 



