MOLLUSCA« 107 
dismembered by modern conchologists, in consequence of 
Lamark having restricted the character in the following 
terms: ‘“ Testa univalvis, conoidea vel subturrita. Aper- 
tura integra rotundata, edentula; marginibus superne sem- 
per disjunctis ; columella basi planulata.” Our T. littoreus 
is now considered as constituting the genus Lirrorina. 
In the genus ScALARIA, the mouth is circular and _ bor- 
dered, with the margins united. The spires are covered 
with raised edged, slightly oblique, longitudinal ribs. The 
famous wentletrap is the type of the genus. 
Lamark thus defines his genus DeLpurnuLa: “ Testa 
univalvis subdiscoidea vel abreviato conica, solida, margari- 
tacea, umbilicata; anfractibus subasperis. Apertura rotun- 
data, marginibus orbiculatim connexis.” The 7. delphinus 
is the type of the genus. There are many species of tur- 
bines common on our shores, which are excluded by the 
preceding characters from the genera turbo and delphi- 
nula, such as the striatus, cingellus, bryereus and others. 
They are distinctly turreted, with the margins of the mouth 
united, and constitute a genus termed CrnGuLA. 
The Turbo terebra of Linnzeus serves as the type of an- 
other genus, termed TuRRITELLA, in which the margins of 
the mouth are disjoined, the spire regularly turreted, and 
the lip emarginated by a sinus. Nearly allied to the pre- 
ceding is the genus PHAsSIANELLA, which Lamark thus de- 
fines: “Testa univalvis, ovata vel conica, solida. Apertura 
longitudinalis, ovata, integra; labro simplici acuto. Colu- 
mella levis basi attenuta. Operculum calcareum vel cor- 
neum animali adherens.” 
Perhaps a rigorous examination of the turbines of British 
writers might justify the formation of one or two new gene- 
ra. In the genus OposTom14, the columella is furnished . 
