[Illustration: FIG. 40.--Larva of the _Libellula depressa_.] [Illustration: FIG. 41.--Larva of the _Agarion virgo_.] Well, then, what is the name of this most singular creature, this masked knight? It is the larva of the _Libellula depressa_; the dismal envelope whence will issue the gaudy Dragon-fly. Listen to a graphic description of the mask you are looking at:-- "Conceive your under-lip to be horny instead of fleshy, and to be elongated perpendicularly downwards, so as to wrap over your chin and extend to its bottom; that this elongation is there expanded into a triangular convex plate attached to it by a joint, so as to bend upwards again and fold over the face as high as the nose, concealing not only the chin and the first-mentioned elongation, but the mouth and part of the cheeks; conceive, moreover, that to the end of this last-mentioned plate are fixed two other convex ones, so broad as to cover the nose and temples; that these can open at pleasure transversely, like a pair of jaws, so as to expose the nose and mouth, and that their inner edges, where they meet, are cut into numerous short teeth, or spines, or armed with one or more sharp claws;--you will then have as accurate an idea as any powers of description can give you of the strange conformation of the under-lip of the larva of those insects, which conceals the mouth and face precisely as I have supposed a similar construction of _your_ lip would do yours. When at rest, this mask applies closely to and covers the face; when they would make use of it, they unfold it like an arm, catch the prey at which they aim by means of the mandibuliform plates, and then partly refold it, so as to hold the prey to the mouth in the most convenient position for the operation of the two pairs of jaws with which they are provided." And so the creature I have been examining is only a larva! How strange to compare it,--thick, ugly, unwieldy,--with the insect that issues from it, so aërial, so graceful, so light, so beautiful! The more I think of the contrast, the more it interests me. This larva, however, has all the characteristics of a perfect insect, and I will wager that more than one observer has described it as such, and classified it among aquatic insects. Yet it is but a larva! And each species has its own special larva (see Figs. 40 and 41). This seems to me as difficult to believe as if you told me that John, James, Peter,--in fact, all men,--were only temporary bodies from which more perfect beings would one day emerge. For the medium in which these masked creatures live,--the troubled and muddy medium for which they are adapted by their organisation, and in which they seem destined to live out their life,--differs wholly and absolutely from the aërial medium wherein, you tell me, they will one day rejoice.