LIMNOPHILIDZ. 
passes around the median plates; the median plates are narrow 
and are separated by not more than the length of a single plate. 
Abdomen.—The spacing humps are flattened ; the dorsal hump 
is surrounded by numerous scattered sete, which are not grouped 
in clusters; on the ventral surface of the segment there is a lip- 
like elevation of the cuticle, which bears a pair of large sete rising 
from dark-colored punctures; in front of the folds the sete are 
scattered over the ventral surface of the segment with no tendency 
to form clusters; the distribution of gills is diagrammatically 
shown in figure 104; each gill has, typically, three branches, ex- 
cept on the last two or three gill-bearing segments, where the num- 
ber of branches is reduced to one or two and the gills themselves 
are weaker. 
PLATYCENTROPUS MACULIPENNIS. 
1o2. Larva. Head and thorax. 104. Larva. Distribution of gills. 
103. Larva. Mandible. 105. Larva. Frons. 
DEscRIPTION OF THE CasE.—Length, 20—25 mm.; breadth, 
7—10 mm. The larve make cases of the typical cross-stick type, 
selecting twigs or grasses of smaller diameter than is usual in the 
genus Limnophilus, and cutting off the loose ends close to the 
case, thus forming a case of more cylindrical and compact appear- 
ance than is usual in this type of case. 
At the caudal end of the case the walls are drawn abruptly 
over, leaving a small circular opening to the tube. 
69 
