VorJiies—Larva of Platyphylax Designatus. 109 
■ously dragged away to a new retreat by a visible brown head 
and six legs. Hundreds of these larvae may be seen in a few 
minutes time in this one group of springs. 
The case is very beautifully constructed of sand grains, and 
is in the form of a slightly curved tube, (Fig. 21.) open at both 
ends, though the posterior, narrower end, usually has the mar¬ 
gin turned in so as to partially close the orifice. (Fig. 22.) The 
concavity of the case is ventral and a slight projection or hood 
extends forward from the dorsal portion of the anterior mar¬ 
gin. 
The eggs of this caddis-fly are deposited in large numbers in 
April. They are attached to the lower surfaces of loose stones, 
mostly at the edge of the water, in very moist situations. The 
larvae hatch in a short time, probably in less than two weeks, 
though the exact time has not yet been determined. They are 
.about 1% mm. in length wdien first hatched, and their heads 
are larger and legs longer relatively than the same parts of 
older larvae. The interesting fact was noticed that these newly 
hatched larvae are positively heliotropic to a marked degree 
when on a dry surface, but at once become negatively helio¬ 
tropic when placed in a dish of water. The necessity of getting 
out from beneath the stones where the eggs are placed in order 
to find water, and of getting beneath stones for protection while 
building a case, after reaching it, offers an explanation of this 
peculiarity. The young larvae at once begin building cases 
when placed in a dish of water with sand in it, and are capable 
of fashioning a fairly good one in four or five hours. They 
probably do not feed until safely housed in a case. Small larvae 
a few millimeters in length are plentiful in the late summer and 
early fall. From November to January" more and more larger 
larvae are found and small individuals become few in number. 
About the middle of February the majority of the cases are 
found to have larger irregular stones attached to the anterior 
ends, evidence of the approach of pupation, while some are found 
fastened to the lower surfaces of the large rocks by a mass of 
silk at the anterior end. Many of the latter are also closed 
at the posterior end with larger stones of the same kind as 
those already mentioned. If the closed cases be broken open 
