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Fig. 5, Nos. 1, 2 and 3); orin compactly formed sense organs 
(Fig. 5, No. 4). 
Fig. 3. Isolated sensory cells. 1 and 5. Cells showing nerve fibres passing to the 
central nervous system. 2, 3 and 4. Isolated sensory cells from prostomium, From silver 
preparations. 
Fig, 4. Isolated and grouped sensory celis. 1, 2 and 3. Groups of sensory cells 
from the tube region. 4, 5 and 6. Isolated sensory cells from the tube protected portion 
of the body. 7. Isolated cell from the second body segment bearing two tactile hairs. 
From silver preparations. 
A. An isolated sense cell is, as a rule, jug or flask shaped 
(Fig. 3, Nos. 1—5), and sharply marked into body and neck portions. 
The body is 5 w to 10 « in width, and from 4 u to 7 u in height, 
