LIMNOPHILID&. 
The genus offers many unsolved problems, such as the func- 
tion of the gill-like structures on the first abdominal segment in 
certain species, and the morphological changes that take place dur- 
ing the long prepupal period. 
THE Case.—In length the case, figure 120, is about 13 mm. 
It has the form of a cylinder, made of fine sand grains, tightly 
cemented with tough, brittle silk. The cylinder is slightly curved 
toward the ventral side. Along the sides of the case there are 
several flat ballast stones. 
In the prepupal or pupal state, the condition in which the cases 
are almost always found, the ballast stones are larger than those 
used during the active period, and each end of the cylinder is 
capped with a large pebble, figure 119. 
Larve of at least two undescribed species were collected. 
NEOPHYLAX CONCINNUS. 
Hasrtat.—tThe species, in the immature stages, is common in 
the riffles of most upland streams of the region, such as Spherium 
Stream, Michigan Stream, and many others. It does not seem 
to occur in spring basins; nor is it common in the warm water 
of the lowlands, though a few specimens have been found in Cas- 
cadilla Creek and in Coy’s Glen. 
LarvaL Hasits.—During the winter and early spring the 
larve crawl over the stream’s bottom, feeding and storing up fat 
to carry them over the long prepupal period, lasting through the 
entire summer. As spring advances they seek the support of 
some solid object, such as a submerged rock or log. Here the cases 
are firmly attached, often great numbers of them on a single 
rock, with the bodies parallel, like cords of wood. 
In late spring, when the larve have attained full size and have 
attached their cases to some solid object, the sieve nets are spun 
across the ends of the cases, and the prepupal state begins. 
In sealing the case the larva does not cover the ends with a 
silken mesh, as do other species of the family, even when flat stones 
also are used. Neophylax selects a stone for each end of the 
case that is slightly larger than the diameter of the tube. These 
stones are tightly cemented over the ends of the case with thick 
sheets of cement-like silk. On the ventral surface of the cephalic 
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