MATERIAL FOR STUDY. 5 
sea-weeds, on logs and sticks, and are sometimes at- 
tached to the shells of mussels. Find them at low 
tide and transfer them to a marine aquarium, made by 
filling a jar with salt water and introducing some marine 
plants collected on the rocks where 
the campanularians are found. Some 
closely related colonies are called 
sertularians. Hydractinia is the 
name given to a colony consisting 
of pink, salt-water hydroids found 
growing on the snail-shells occu- 
pied by hermit-crabs. 
Sea-anemones. These animals 
are hardy and may be transported 
for some distance in jars or pails of 
salt water. To obtain them, look 
in pools left by the tide in rocky 
places, or on rocky bottoms below se allan Sars 
lowtide. They are sometimes found Agassiz. si " 
attached to the piles of wharves or 
bridges. They can be removed from the rocks by 
quickly slipping a broad, thin knife between the 
anemone and the rock. Their resemblance to hydras 
and to coral animals 
should be especially 
noted. Except as 
living specimens they 
are not of much value 
to beginners, as the 
prepared specimens 
are commonly too 
Fic. 21.—A Net for Collecting at the much distorted to 
Seaside. 
‘ ay) 
show structure well. 
Starfishes and Sea-urchins. These animals may 
be found in the same localities as the anemones. They 
are quite hardy and will live in salt-water aquaria. As 
they can be collected at any time during the year, it is 
as well to get the living specimens when ready to study 
