The piece of amber, now on the table, was found in the kingdom of Ava, and sent to me from India by the late Mr George Swinton, to whom the Society was indebted for many interesting objects of natural history from that country. It weighs 2½ lbs., and in its general aspect seems to differ considerably from the ordinary specimens of amber. The remarkable fact, however, which distinguishes it from all the specimens of amber I have seen or read of, is, that it is intersected in various directions by thin veins of a crystallised mineral substance. These veins are in some parts of it as thin as a sheet of paper, and in other parts about the twentieth of an inch thick. In order to determine the nature of the mineral I extracted a portion of the thickest vein, and having obtained, by cleavage, a small rhomb, I succeeded in measuring the inclination of its planes, and found it to be carbonate of lime.