126 CLASS III]. GASTEROPODA. ORDER VII. PECTINIBRANCHIATA. 
VALVATA, Miller. 
Testa spiralis, spira discoidea, vel elevatiuscula, anfractibus rotundis, 
convexis, ultimo umbilicum amplum formante ; apertura circulari, 
margine continuo, labro simplici, acuto. Operculum corneum, 
spirale. 
The shell of this little mollusk, distinguished by Muller with the title 
of Valvata, appears to have been first noticed by Geoftroy ; it nevertheless 
escaped the attention of Bruguiére, and for a long time that of both Cuvier 
and Lamarck. The genus Valvata was, nevertheless, adopted by these 
authors upon the revival of it by Draparnaud: upon noting the great 
resemblance that exists between the shell of Valvata and that of Cyclo- 
stoma, he at first referred it to that genus, but was subsequently led by 
the marked difference in their habits to appreciate the distinction allotted 
to it by Miiller. 
The shell of Valvata may be described as being spiral, with the spire 
either discoid, or rather elevated ; the whorls are round, and convex, the 
last forming a large umbilicus ; the aperture is circular, with the margin 
continuous, and the lip is simple and acute. The operculum is horny 
and spiral. 
The Valvate, which are small, and not very abundant, are generally 
found upon aquatic plants, &c. in ponds and ditches. 
Examples. 
Pl. CXCVL. Fig. 1. 
Vaxvata piscinaLis, De Férussac, Syst. Conch., p. 
Manuel de Malacologie, pl. 34. f. 4. 
Le porte-plumet, Geoffroy. 
75. De Blainville, 
Helix piscinalis, Gmelin. 
Turbo cristatus, Poiret. 
Cyclostoma obtusum, Draparnaud. 
