58 GASTEROPODA. HELICID. 
Shell spiral ; the last whorl very large. Aperture large, ob- 
lique, its hinder extremity acuminated on the right side. Pe- 
ritreme none. Umbilicus none. Tentacula short ; upper ones 
somewhat conic; under ones very short, tuberculiform. 
The animal during the summer months can scarcely retire 
within its shell. 
1. Succinea MULUERI. 
S. test& ovato-oblongé, diaphana, cornea ; apertura ovato-ob- 
longa. 
Helix putris, Donov. Brit. Shells, t. 168. fig. 1; Mont. Test. 
Brit. u. 376. t. 16. fig. 4; Dill. Desc. Cat. 965. 
Helix succinea, Mill. Verm. Hist. 296; M. and R. Trans. 
Linn. Soe. vii. 218; Turt. Conch. Dict. 67. 
Succinea amphibia, Drap. Hist. Moll. 58. pl. 3. fig. 22. 
Lymnea succinea, Flem. Edinb. Encyel. vii. 77. 
(. testa elongata, alioquin varietati, a. simillima. 
Helix succinea, Drap. loc. cit. pl. 3. fig. 24. 
Habitat in paludibus ; nympheeaceis, juncis salicibusque, affixa. 
Shell ovate-oblong, diaphanous, corneous; the aperture ovate- 
oblong. Variety (. differs merely in being more produced. 
Animal blackish, extremely mucous, forming a hard epi- 
phragm for the winter. 
Inhabits marshes, attaching itself to aquatic plants, as well 
as to such trees as grow in wet grounds. Height of the shell 
five-fourths of an inch. 
Young shells are often tinted with pale green, which gradually 
changes into horn or amber colour during their growth. 
This is the only species yet discovered to inhabit Britain. 
It has been strangely confounded with very different species 
belonging to other genera. 
STIRPS II. 
Synopsis Generum. 
Peritrema nullum #4 22000075 ool e8 L . ...0828. ee 
Peritrema tenue, reflexum; posticé nullum.. 24. Hetrx. 
