(_Planorbis corneus_.)
The _Planorbis_, although differing in form from the Lymnæa, possesses
the same habits, and is found in the same localities. The jelly-like
substance which is frequently found, in the Spring of the year,
attached to water-cresses and other aquatic plants, and which is
considered by many to be of a poisonous nature, and looked on as the
spawn of toads, is merely the covering of the ova of this and other
inhabitants of fresh-water shells; and, although very disagreeable,
certainly not poisonous.