M. Daubenton, who has more minutely inspected the nature of bezoar stones than any other person, thinks they are composed of something similar to that which fastens itself to the teeth of ruminating animals in the form of a shining tartareous matter; and it is evident, from the collection of bezoars, of which there are a great number in the royal cabinet, that there are essential differences between the oriental and occidental bezoars. Thus the East Indian goats, or the gazelles of Persia, are not the only animals which produce the concretions, called bezoars for the chamois, and, perhaps, the wild goat of the Alps, the he-goats of Guinea, and many animals of America, afford this substance; and, if we comprehend under this name all concretions of this nature, which are met with in different animals, we may be assured, that most quadrupeds, excepting carnivorous ones, and even crocodiles and alligators, produce bezoars. To form, therefore, a clear idea of these concretions it will be necessary to divide them into several classes, and refer them to the animals which produce them, and the climates and food which mostly assist in their production. First, then, the stones formed in the bladder and kidneys of men, and other animals, must be distinguished from the class of bezoar, and described by the name of _calculi_, their substance being quite different from that of the bezoars; they are easily known by their weight, their urinous smell, and their structure, which is not regular, nor formed with concentric layers, like that of the bezoar. 2. The concretions that are often found in the gall-bladders and liver, of the human species, and other animals, must not be regarded as bezoars; they may easily be distinguished by their lightness, colour, and inflammability; besides they are not formed by layers encircled round a nucleus, as in the bezoar. 3. The balls frequently found in the stomachs of animals, and especially in those that ruminate, are not true bezoars. These balls, which are called _ægagropili_, are composed internally of the hair the animal has licked off his hide and swallowed, or from hard roots, which he could not digest, their external part is encrusted with a viscous substance, something like that of the bezoar. The _ægagropili_, therefore, have nothing in them, except this external layer, in common with the bezoar, and simple inspection is sufficient to distinguish one from the other. 4. _Ægagropili_ are often found in the animals of temperate climates, but never any bezoars. Our oxen and cows, the Alpine chamois, and the porcupine of Italy, produce only _ægagropili_. Animals of hotter countries, on the contrary, only produce bezoars. The elephant, the rhinoceros, the goats, the gazelles of Asia and Africa, the lama of Peru, and others, produce, instead of _ægagropili_, solid bezoars, whose substance and size vary according to the difference of the animals and the climates in which they live.