In the above few remarks we have alluded to some features by which the two great groups of the _Lepidoptera_ may be distinguished; but we have already referred (page 5) to a far more important one in our description of the various forms of antennae. All butterflies--at least all _British_ butterflies--have knobbed or clubbed antennae, while the corresponding organs of all our moths terminate in a sharp point. This distinction obtains in all British _Lepidoptera_, and is so far regarded as the most important basis of classification that naturalists have derived from it the two Greek terms that are synonymous with our two popular names--butterflies and moths. The scientific name for the former group is _Rhopalocera_--a term derived from two Greek words, one signifying a horn, and the other a club, and thus meaning 'club-horned.' The corresponding name for moths is _Heterocera_, derived from the same source, and meaning 'variously horned.' But, although we find embodied in these two long and formidable names an unerring mark of distinction between British butterflies and moths, we must not neglect other less important facts which, though less distinctive, are not without interest. Observe a butterfly at rest. Its wings are turned vertically over its back, and brought so closely together that they often touch. In this position the 'upper' surfaces of the 'upper' wings are completely hidden from view, and the 'under' surfaces are exposed on the two sides, except that those of the 'upper' pair are partly hidden by the other pair. Now look at a moth under the same circumstances, and you will generally find the wings lying over its body, which is almost or completely hidden beneath them. As a rule the upper pair together form a triangular figure, and entirely cover the second pair; but in some cases a portion of each of the under wings extends beyond the margin of those above them, and in others the upper pair extend so far forward that nearly the whole of the under wings is exposed behind them. [Illustration: FIG. 37.--A BUTTERFLY AT REST (LARGE COPPER).] [Illustration: FIG. 38.--A MOTH AT REST (GOTHIC).] Again, the wings of butterflies are so rigid that they can never be folded; but you will observe that the under wings of moths are generally very thin, soft, and pliant, and are neatly pleated lengthwise when not in use. Another feature deserving notice is a slight difference to be often observed in the form of the body. The butterfly, which generally has a slender body, has a distinct constriction or waist between the thorax and abdomen. This is not so apparent with moths, and especially with the thick-bodied species. The _Rhopalocera_ or Butterflies are divided into _Families_, each of which contains insects that possess certain features in common by which they may all be distinguished from the members of any other family. The British species represent eight families. They are as follows: