272 Annals Entomological Society of America -[Vol. VII, 
PLATE XXXVI. 
Photos by J. T. Lioyp. 
Photo 1. Cascadilla Creek below Fish Hatchery. Taken in midsummer when 
the water is low to show character of creek bed. Earlier in the season, 
the Hydropsyche nets stretched between the stones on the boiiom are 
very numerous. In the quiet water at the left the larvae of the Family 
Polycentropide are found. 
Photo. 2. Cascadilla Creek in the spring as it rushes over the shelving ledges 
beside the Hatchery. A favorite spot of the Hydropsyche larvae. 
Photo 3. Trough where experiments were carried on. Water entered through 
pipe above, and spilled over at corners at lower end, through grooves in 
the sides, where the Hydropsyche larvae built perfect catching-nets. 
Under the trough is a water-glass used in field work, and beside it, a fold- 
ing bench for use while making observations in the stream. 
PLATE XXXVII. 
Fig. 1. Diagrammatic figure of a house of Hydropsyche angustipennis, copied from 
Wesenberg-Lund (1911) (Plate IV, Fig. 22). At the left is the tube in which 
the larva lives. In front of it is a vestibule with a catching surface of fine 
mesh in its side wall. Near this net is the opening of the larval tube. 
Fig. 2. A typical Hydropsyche dwelling in which the coarse, irregular mesh- 
work of the net is not strengthened by any supporting bits. Enlarged x 2. 
Fig. 3. End view of one of the grooves of the trough with the Hydropsyche 
dwelling built in it. 
Fig. 4. Hydropsyche dwelling built in trough, and viewed from above. 
Fig. 5. Usual position assumed by the Hydropsyche larva in spinning its net 
or in feeding. 
PLATE XXXVIII. 
Fig. 1. Catching-net of Chimarrha aterrima. Natural size. 
Fig. 2. Dwelling of Cyrnus pallidus (?). Larva lives in the tube, and at either 
opening is the catching-net. This is composed of radiating strands of 
silk fastened at their outer ends to the stone, and connected with one 
another by anirregular mesh. Enlarged x 2. 
Fig. 8. Dwelling of Polycentropus sp. (?) Delicate silken tube in which larva 
lives, slightly curved, and surrounded on all sides by a delicate irregular 
mesh which functions as a catching-net. Enlarged x 2. 
