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OVULA. 
Gen. Char. A more or less ovate and gibbose 
convoluted univalved shell ; the spire con- 
cealed ( or rather none ) ; aperture longitudi- 
nal, elongated, narrowest at its upper part; 
the extremities more or less produced, notched; 
inner lip toothless; outer lip thickened, in- 
curved. 
A genus well distinguished from Bulla, under which 
Linnaeus had placed its species. It approaches so near 
to Cypraea, that most conch ological authors notice 
its resemblance ; but unlike that genus its species are 
rarely of more than one colour externally, and never 
variegated. The whole of the outer surface of the 
shell is when full-grown covered with an enamel-like 
coat, which is in fact a continuation of the columellar 
lip : hence that lip (which is itself in other shells only a 
production of the lining) appears to be wanting : as 
this coat generally marks the distance the mantle of the 
animal is able to reach, it is supposed that the animal of 
an Ovula has a mantle constructed so as to inclose the 
whole shell, and bipartite, as in Cypraea, which has a si- 
milar coat. The genus is known by the incurved 
thickened outer lip of the aperture, opposite to the 
ventricose smooth body of the shell, instead of to a row 
of teeth or obtuse laminae as in Cypraea ; some species 
have a single plait upon the upper part of the co- 
lumella. The surface is seldom or never furrowed. 
