LXVII. An account of a stony concretion taken from the colon of an horse

Read May 8, IT Have now the honour to lay before this I?6o‘ JL Royal Society one half of a ftony con­ cretion, formed in the colon of an horfe, which was lately fent me from Norwich, by my very curious friend Mr. William Arderon, F. R. S. This horfe, he informs me, was twenty-five years old, had been often ill, and under the farrier's care; which made him defire to have it opened, when dead. The whole ftone, when firft taken out, weighed ten pounds and half; and he caufed it to be fawed in two, that a better judgment might be made of the manner of its formation. Several fmaller concretions were alfo found in the colon, fome whereof are fhewn herewith; but they are much lefs folid, and more irregular, than the large one. This ball is full feven inches in diameter, and confifts of many laminae, or coats, which form a num­ ber of concentric circles, around a nucleus in the center, which feems to be a fmall fhiver of black flint. Fifteen or fixteeen of thefe coats are ealily diftingui(liable, and fome have been broken off; they vary fomething in colour, and are, in general, f© ftony, that they would probably take a pretty good polifh. The coats differ in thicknefs, according, per­ haps, to the time they were in forming: for it fhould feem, if conjecture may be allowed, that each coat was formed in a longer or (horter time, according to