RHYACOPHILID&. 
The Thorax—The prothorax above is straw yellow, with a 
caudal margin of deep black; each episternum is extended for- 
ward in a spine-like process which has a black dorsal spot; the 
legs are straw yellow. 
RHYACOPHILA TORVA. 
190. Larva. Head and thorax. 192. Larva. Prolegs, lateral view. 
191. Larva. Frons. 
The meso- and meta-thorax are brown in alcoholic material, 
marked with light yellow, as in figure 190; the second and third 
pairs of legs are almost white. 
The Abdomen.—The abdomen is narrower and less flattened 
than that of R. fuscula, the constrictions between segments are not 
quite so deep, and dorsal furrows of the integument are absent. 
Each segment has a similar dorsal pattern of light color, as shown 
in figure 190. The drag-hooks, figure 192, are slender and very 
simple compared to those of R. fuscula; there are no lateral spine- 
like elongations of the chitin, no dorsal humps at the base of the 
claws, and no ventral back-turned hooks. The drag-hooks are 
long and slender and comparatively weak. 
DrscrIPTION OF CasE.—We have made no observations on 
the case-building habits of the species. Vorhies, who reared it in 
Wisconsin, states that “the larva lives in a loosely-built case of 
gravel,” and “at the time of pupation this becomes a strong, irregu- 
II5 
