VALVATIDA. 273 
Geometride. As the animal proceeds, the rostrum and the small 
foot are moved alternately. 
PALUDINELLA, Pfeiffer. Shell turbinated, oval or depressed, 
umbilicated ; whorls rounded; aperture subcircular, lip simple, 
usually continuous. Amphibious, living in marshes usually near 
the sea. A. littorea, Chiaje (xxiii, 18). 
ACMELLA, Blanford. Shell ovate, with a corneous epidermis ; 
aperture ovate, the margin obtuse. Operculum corneous, thin, 
paucispiral. Animal like Assiminea, with short proboscis, ten- 
tacles short obtuse, with eyes on their sides, foot moderate, obtuse. 
A. tersa, Benson (Ixxiii, 94). Damp places, Khasi hills, India. 
A land rissoid allied to Assiminea. 
HYDROCENA, Parreyss. (Georissa, Blanf.) Shell imperforated 
or umbilicated, elobosely turbinated; aperture oval. Operculum 
thin, corneous paucispiral. Dalmatia, India. Terrestrial. A. 
Cattaroensis, Pfr. (1xxiii, 95). 
LAGUNCULA, Benson, 1856. (Bensonia, Cantraine.) Shell tur- 
binated, subglobular; aperture oblong, large; outer lip a little 
reflected ; umbilicus profound, tortuous. A. pulchella, Benson. 
Chusan. 
Famity VALVATID A. 
Shell depressed conical or almost discoidal; umbilicated ; 
covered by a thin greenish epidermis. Operculum orbicular, 
corneous, multispiral. 
Animal with a produced muzzle; tentacles long and slender, 
eyes at their outer bases ; foot bilobed in front ; branchial plume 
long, pectinated, partially exserted on the right side, when the 
animal is walking. Lingual teeth broad; uncini 3, lanceolate ; 
all hooked and denticulated (xi, 24). 
Vatvata, Miller. 
Syn.—Valvatinella, Betta. Cincinna, Hiibn. 
Distr.—Fresh water, mundane. V/V. piscinalis, Mull. (1xxiii, 96). 
Shell depressed conical (in the typical group). Other charac- 
ters, those of the family. 
The species are of small size, living in ponds and ditches and 
slow-running water, principally i in North America and Europe. 
When the animal Ae moving, the delicate, retractile branchial 
plume is projected over the neck. The female deposits her eggs 
in a single, coriaceous, spherical capsule, which is affixed to 
stones or the stems of aquatic plants. 
GYRORBIS, Fitzinger. (Planorbitina, Betta. Planella, Schliit.) 
Shell discoidal, depressed, widely umbilicated, whorls ‘younded. 
Europe, America. V. cristata, Miiller (1xxiii, 97). 
TROPIDINA, H. and A. Adams. Shell turbinated, whorls’ 
carinated. N. America. V. tricarinata, Say (1xxiii, 98, 99). 
