Many papers have been written about caddis cases, treating these movable shelters from the standpoints of choice of materials (Brues 1930, Dodds & Hisaw 1926, Lloyd 1915, Lutz 1930, Simpson 1903), of repair (Marshall & Vorhies 1905), of ontogenetic initiation (Murphy 1919, Copeland & Crowell 1937), and of phylogenetic origin (Milne & Milne, 1938). The last of these references, a paper by Sleight (1913) and the work of Dodds & Hisaw cited above, give some attention to the relation between case-building and the physiology of the larva inhabiting the structure, but much remains to be studied in this connection.