770 Eatracts from the Minute- Book of the Linnean Society. 
flexible and extensile, and, either separately or collec- 
tively, can be protruded beyond the caudal segment, 
or retracted within it, at the pleasure of the animal. 
Their efficiency as a cleaning apparatus, and an organ 
of adhesion and progression, depends principally upon 
the mucus they emit, which is secreted in great abun- 
dance, and not upon the power of producing a vacuum. 
When this instrument is applied to the body of the 
insect, any extraneous matter immediately becomes 
attached to it, and the impurities thus collected are 
ultimately expelled by a fresh discharge of mucus and 
a peculiar motion of the papillz." 
CATALOGUE 
