THE ENTOMOLOGIST. 243 
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 a 
seven-thousandth to a two-thousandth 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. No pellets of earth are ever interwoven with the 
silk to form the outer layers of the walls, though the adhesive 
nature of the silk when freshly spun causes fragments of earth 
to remain attached to the surface. The mouth of the tube is 
commonly dilated a little, so as to forma 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 thick- 
ening of the hinge by additional layers is, 1 think, accidental 
only, as out of the many specimens 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. 
“One of peculiar compactness, now before me, I have slit 
open longitudinally with a pair of scissors in the manner 
spoken of above: the thickness of the substance is in no 
place greater than one-sixteenth of an inch, which is very 
regularly maintained throughout the lid and upper parts. The 
appearance at the cut edge closely resembles mill-board so 
divided; the layers of which it is composed being very 
numerous and compact, especially towards the interior side, 
where they can scarcely be distinguished even with a lens. 
In this specimen there is what I cannot find in any of the 
others [ have examined. A row of minute holes, such as 
might be made by a very fine needle, are pierced around the 
free edge of the lid, and a double row of similar holes just 
within the margin of the tube. There are about fifteen or 
sixteen punctures in each series, and they penetrate through 
the whole substance, the light being clearly seen through each 
hole. Now what is the object of these orifices? 1 do not 
think, as I have somewhere seen suggested, that they are 
intended to afford a hold for the spider’s claws when she 
