MODE OF BUILDING 109 



valves of a small mussel, and fastened them back 

 to back on its house. Beside these, there are one 

 or two very eccentric forms, where the caddis has 

 chosen some objects which are not often seen in 

 such a position. The seed-vessels of the elm are 

 tolerably common ; but I have several specimens 

 where the caddis has taken the operculum of a 

 dead pond-snail, and fastened it to the case ; and 

 there is an example where the chrysalis of some 

 moth, apparently belonging to the genus Porthesia, 

 has been blown into the water from a tree over- 

 hanging the stream, and seized upon by a caddis 

 as a unique ornament for its house. These 

 latter examples were found in a stream in Wilt- 

 shire, and the tusk-like sand-cases were found in 

 a disused stone-quarry in the same county. 



' Various experiments have been tried upon the 

 larva of the caddis, in order to see its mode of 

 building. A lady, Miss Smee, has been very 

 successful in this pursuit, and has forced the 

 caddis larvse to build their nests of the most 

 extraordinary substances, such as gold - dust, 

 crushed glass, and other substances. They 

 would not, however, use beads, or anything 

 where the surface was smooth and polished. 



' In this remarkable sub-aquatic home the caddis 

 larva lives in tolerable security, for the head and 

 front of the body are clothed in horny mail, and 

 the soft white abdomen is protected by the case. 



