For the slow-moving reptile the scales suffice, preserving it from hurtful contacts, but playing hardly any part as a bulwark against changes of temperature.
In its liquid environment, which is far more constant than the air, the fish requires no more. Without effort on its part, without violent expenditure of motor force, the swimmer is borne up by the mere pressure of the water. A bath whose temperature varies but little enables it to live in ignorance of excessive cold or heat.
In the same way, the mollusc, for the most part a denizen of the seas, leads a blissful life in its shell, which is a defensive fortress rather than a garment. Lastly the crustacean confines itself to making a suit of armour out of its mineral skin.
In all these, from the hairy to the crustaceous, the real coat, the coat turned out by a special industry, does not exist. Hair, fur, feather, scale, shell, stony armour require no intervention of the wearer; they are natural products, not the artificial creations of the animal. To find clothiers able to place upon their backs that which their organization refuses them, we must descend from man to certain insects.
Ridiculous attire, of which we are so proud, made from the slaver of a caterpillar or the fleece of a silly sheep: among its inventors the first and foremost is the Crioceris-larva, with its jacket of dung! In the art of clothing itself, it preceded the Eskimo, who scrapes the bowels of the seal to make himself a suit of dittos; it forestalled our ancestor the troglodyte, who borrowed the fur-coat of his contemporary the Cave-bear. We had not got beyond the fig-leaf, when the Crioceris already excelled in the manufacture of homespun, both providing the raw material and piecing it together.
For reasons of economy and easy acquisition, its disgusting method, but with very elegant modifications, suits the clan of the Clythræ and Cryptocephali, those pretty and magnificently coloured Beetles. Their larva, a naked little grub, makes itself a long, narrow pot, in which it lives just like the Snail in his shell. As a coat and as a dwelling the timid creature makes use of a jar, better still, of a graceful vase, the product of its industry.
Once inside, it never comes out. If anything alarms it, with a sudden recoil it withdraws completely into its urn, the opening of which is closed with the disk formed by the flat top of the head. When quiet is restored, it ventures to put out its head and the three segments with legs to them, but is very careful to keep the rest, which is more delicate and fastened to the back, inside.
With tiny steps, weighted by the burden, it makes its way along, lifting its earthenware container behind it in a slanting position. It makes one think of Diogenes, dragging his house, a terra-cotta tub, about with him. The thing is rather unwieldy, because of the weight, and is liable to heel over, owing to the excessive height of the centre of gravity. It makes progress all the same, tilting like a busby rakishly cocked over one ear. One of our Land-snails, the Bulimus, whose shell is continued into a turret, moves almost in the same fashion, tumbling repeatedly as he goes.
The Clythra's is a shapely jar and does credit to the insect's art of pottery. It is firm to the touch, of earthy appearance and smooth as stucco inside, while the outside is relieved by delicate diagonal, symmetrical ribs, which are the traces of successive enlargements. The back part is slightly dilated and is rounded off at the end with two slight bumps. These two terminal projections, with the central furrow which divides them, and the ribs marking additions, which match on either side, are evidence of work done in two parts, in which the artist has followed the rules of symmetry, the first condition of the beautiful.
The front part is of rather smaller diameter and is cut off on a slant, which enables the jar to be lifted and supported on the larva's back as it moves. Lastly, the mouth is circular, with a blunt edge.