These Worms are inclosed in a Shell, which is grayish and of the bigness of a Barly-corn, sharper at one end, than the other. By the means of an excellent Microscope I have observ'd, that 'tis all overspread with little Stones and little greenish Eggs; and that there is at the sharpest end a little hole by which these Creatures cast out their excrement, and at the other end, a somewhat bigger hole, through which they put out their heads and fasten themselves to the Stones, they gnaw. They are not so shut up, but that sometimes they come out, and walk abroad. They are all black, about two Lines of an inch long and three quarters of a Line large. Their Body is distinguish't into several plyes, and near their head they have three feet on each side, which have but two Joynts resembling those of a Lowse. When they move, their Body is commonly upwards, with their mouth against the Stone. They have a big head, somewhat flat, and even, of the colour of a Tortoise-Shell, braunish, with some small white hair. Their mouth is also big; where may be seen four kinds of Jaw-bones, lying crossewise, which they move continually, opening and shutting them like a pair of Compasses, with four branches. The Jaws on both sides of the mouth are all black, the nether Jaw hath a point like the Sting of a Bee, but uniform. They draw threds out of their mouth with their fore-feet, using that point to range them, and to form their Shells of them. They have Ten Eyes, very black and round, which appear to be bigger than a Pins head. There are five of them on each side of the head, standing after this manner,
But besides these Worms, I have found, that Mortar is eaten by an infinite number of small Creatures, of the bigness of Chees-Mites. These have but two Eyes, and are blackish. They have four feet on each side pretty long. The point of their Muzzle is very sharp, as that of a Spider. I send you but one of them, though I had abundance, but they are dead and lost. It may be, you'l find some at Paris, seeing that in the old Mortar betwixt Stones, that is found in Walls made with rubbish, there is great store of them, together with great plenty of their little Eggs. I have not yet examined, whether these be those, that in the surfaces of all the Stones, where they are met with, make little round holes, and small traces and impressions, which make them look like Worm-eaten Wood. But 'tis probable, they are such. It should be observed, whether these Worms do not take Wings, and all the other appearances of Caterpillars; and whether they are not to be found in plaister that is full of holes, in Bricks, in Greety Stones, and in Rocks.
You may observe more of them in Walls exposed to the South, than in others; and that the Worms, that eat the Stone, live longer, then those,
that eat the Mortar, which keep not above eight days alive. I have observed all their parts with a very good Microscope, without which, and a great deal of attention, 'tis difficult to see them well.
I have seen other very old Walls altogether eaten, as those of the Temple at Paris, where I could find no Worms, but the Cavities were full of Shells of various kinds, diversly figur'd and turn'd: all which I believe to be little Animals petrified.
Some promiscuous Observations, made in Somerset shire, and imparted by the above-mentioned Dr. Beale.
His words are these, in a Letter to the Publisher, of the 24. Septemb. 1666 at Yeovill in Somersetshire;