128 
Psyche 
[December 
minutes. It is clear that the formation of the girdle, the 
initial and most difficult step in case-building, is accomplished 
here by a quite different method than in the limnephilid. 
The larva remains partly buried in the sand and by adding 
sand grains to the anterior edge of the girdle extends it to 
form a tube. This is similar to the method employed by the 
limnephilid in completing its case. 
The hood which overhangs the anterior opening of the 
tube is constructed as soon as the latter is finished, but its 
backward extensions (flanges) on either side of the tube may 
not be completed for one or two days. 
On several occasions a larva of Molanna was put into a 
dish with only a small amount of sand, that is with an 
amount insufficient to permit the burrowing and tunnel 
formation as described above. Under these circumstances 
the larva forms the girdle in a somewhat different manner, 
as follows : The larva collects sand grains into a small pile 
beneath itself. These are then joined loosely together by 
the salivary secretion. The larva then thrusts its head into 
this loosely aggregated mass of sand. If the sand holds to- 
gether on all sides the larva thus surrounds itself with a 
girdle. Often the mass of sand breaks apart as the larva 
burrows into it. When this occurs the procedure is repeated . 1 
From this it appears that a Molanna larva, when there is 
only a small amount of sand, forms the girdle by burrowing, 
even though this is difficult and often unsuccessful. Since no 
attempt is made to form a girdle by wrapping the aggregated 
sand grains around itself, the method is not like that em- 
ployed by the limnephilid, a procedure which might be more 
effective than the one actually used. It seemed to us that 
this method of girdle formation very closely resembled that 
employed by Molanna in deep sand, the only difference con- 
sisting in the cementing together of some sand grains before 
burrowing commenced. 
It is well known that caddis-fly larvae are able to employ 
unusual materials in the construction of cases. We found 
that the limnephilid larvae were able to build cases of small 
Tfembowski (1933) reports one case in which a larva of Molanna , 
receiving an insufficient supply of building material, burrowed between 
the pile of material and the glass bottom of the dish, ultimately using 
the dish as the under side of its case. 
