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 perhaps where the mould is liable to fall in; and thus I account for the loose rough laminæ of silk that are always found projecting from the outer surface. These are overlaid with other patches more and more extensive, until the whole interior walls are covered; after which the silk is spun evenly and continuously all round the interior, in successive layers of very dense texture, though thin. Under the microscope, with a power of 220 diameters, these layers are resolved into threads laid across each other and intertwined in a very irregular manner; some are simple, varying from 1/7000 to 1/2000 of an inch in diameter, and others are compound, several threads, in one part separate, being united into one of greater thickness which cannot then be resolved The mouth of the tube is commonly dilated a little, so as to form a slightly recurved brim or lip; and the lid is sometimes a little convex internally, so as to fall more accurately into the mouth and close it.

The thickening of the hinge by additional layers is, I think, accidental only, as, out of the many specimens that I have examined, only one or two had such a structure. In the neatest examples, the lid is of equal thickness throughout its extent, agreeing also with the walls for the first few inches of their depth."

Mr. Gosse says that he possesses one specimen of peculiar compactness, which differs from all the others that he has examined in having "a row of minute holes, such as might be made by a very fine needle, pierced around the free edge of the lid, and a double row of similar ones just within the margin of the tube. There are about fifteen or sixteen punctures in each series, and they penetrate through the whole