124 LIFE AND HER CHILDREN. 
touch, and sensitive nerves. Especially their smell 
is very acute, probably in order to prevent them from 
venturing into bad water where their delicate and 
unprotected gills would be unable to work well. 
Though they are so fragile -looking, yet they eat 
ravenously, feeding on young corals, sertularias, and 
sponges, and often digging a good piece of flesh out 
of a sea-anemone with their scoop-like rasp. Some 
Fig. 47- 
Naked-gilled Mollusca, commonly called sea-slugs. Alder and Hancock. 
D, Doris pilosa. E, Eolis coronata. f, Foot ; g, breathing-gills; 
t, tentacles. 
of them are protected by spicules set in their flesh, 
but most of them are very tender, and escape obser- 
vation by the wonderful resemblance of their colours 
to those of the seaweed over which they wander ; and 
whether floating, or hanging by slimy threads, or 
crawling with their beautiful plumes outspread, they 
select chiefly the dark sheltered spots neglected by 
the hardier children of Life. 
