In some species the mother lays her eggs on the trunks of trees, and covers them with down or with the hairs which clothe her abdomen, so as to preserve them from cold and damp. She may also hide them entirely under a whitish foamy substance. Some do not lay more than a hundred eggs; others lay some thousands. To bring the history of the Lepidoptera to an end, it only remains for us to give a sketch of their classification, and to point out some species remarkable, either on account of their beauty or their utility. We see during the day butterflies flying in our gardens, in meadows full of flowers, or in the alleys of woods. Towards evening, at the sombre hour of twilight, the stroller is sometimes surprised to see pass near him large moths, with a heavy and unequal flight; or, if we go into a garden on a beautiful calm summer's night, bearing a light, we see a crowd of moths flying from all parts towards it. It is on account of these different hours at which the Lepidoptera show themselves, that naturalists for a long time divided them into diurnal, crepuscular, and nocturnal. This division was simple, convenient, and seemed founded on Nature. Unfortunately, the _night_ fliers of the old authors do not all fly by night: some species, classed by the old naturalists among the crepuscular, or nocturnal, show themselves in the very middle of the day, seeking their food in the hottest rays of the sun. In the regions near the poles they appear during the day, and in other countries they are more or less friends of the twilight. So as not to multiply methodical divisions, we will confine ourselves to classing the Lepidoptera into two sections. The first section contains those _which fly during the day, which have club-shaped antennæ, and which have their four wings entirely free, and standing perpendicularly[48] when the insect is at rest_. They are called Butterflies, or Rhopalocera. This section is divided into a number of families, which comprise many genera. We will content ourselves with calling the attention of the reader to some of the most remarkable of these groups, and to those species which, either on account of their beauty or abundance, strike, or ought to strike, the attention of every one. [48] There are exceptions to this.--ED. In the family of the _Papilionidi_, we will mention the genera _Papilio_, to which belong the Swallow-tailed Butterfly (_Papilio machaon_), _Papilio podalirius_, &c., and _Parnassius_, of which we will notice _Parnassius Apollo_, and _Parnassius Mnemosyne_. [Illustration: Fig. 139.--Swallow-tailed Butterfly (_Papilio machaon_).] [Illustration: Fig. 140.--Larva and Chrysalis of Papilio machaon.]