CASSIDA, in natural history, a genus of Coleopterous insects, which, accord ing to Linnxus, have moniliform anten nx, that become rather thicker towards the end : thorax and wing-cases with a broad margin, the former flat, and form ing,a kind of shield, beneath which the head is concealed. There are about 90 species.
The rotundate figure of the body, gibbous back, and flattened surface be neath, are a strong criterion of this ge nus. The surface above is commonly smooth, and in some species glossy ; eyes oval, and placed near each other ; antennx inserted between the eyes : scutel triangillir and small ; wing-cases same length as the abdomen ; legs short, thighs compressed, shanks rounded, Ad the tarsi consisting of four joints. Many of the species are very beautiful when alive, some of which retain their bril liancy of colours in the height of perfec tion after death ; in others, however, and those especially of a small size, these are altogether evanescent, their rich me tallic or golden hues fading as the insect dies, and totally disappearing in the dried specimens. Cassidx, immersed in spirit of wine alive, are observed to retain the splendour of those golden hues fbr years, in as high perfection as they appear in the living insect ; but if taken out, and allowed to dry, these change colour, in the same manner as the insect would in dying without being steeped in spirits.
For immediate observation, the true co lours of the living insect may, however, be revived in the dried specimens at any time, by leaving them for the space of 15 or 20 minutes in warm water ; the colours re-appearing while the insect is kept moist, and fading again as the insect dries.
The larva of the cassidx are common ly fbund concealed on the under surface of the leaves of the plants on which they feed, and often hide themselves under a cover of their own excrements, which they support in the air above their bo dies by means of their lateral spines, and the bristles at the extremity of their tail, to shelter from the sun and rain. The lame cast their skins several times before they pass into the pupa state. The perfect female insect deposits the eggs in regular order on the leaves of plants, and covers them with excrements to conceal them. The common English name of the insects of this tribe is the tortoise beetle. We have only an incon siderable number of the species indige nous to this country, and those only of a small size : many of the large kinds, and those distinguished for their vivid hues and colours, are natives of South