The ambulacral zones are depressed, leaving prominent elevations which make a very conspicuous figure on the top.
ambulacral zones: The five areas containing the rows of tube-feet.
Interambulacral areas: The five areas between the ambulacral zones.
ambulacral grooves follow the center of all the arms and branches.
In this family the ambulacral plates have but three pairs of pores.
In both cases also we find the ocular spots at the tips of the ambulacral areas.
In this family the ambulacral plates have several pairs of pores.
The same observations apply to smaller segments, and even to single detached rows of ambulacral feet.
The ambulacral zones, in five petal-like lines, form a distinct figure on the upper surface.
ambulacral appendages take the form of: circumoral tentacles, sucking-feet, papillae; of these alone is always present.