Family I. Asteriadae or Asterocanthiidae

Four rows of ambulacral feet. Fam. 2. Astropectinidae. - Two rows of ambulacral feet; back flattish, netted with tubercles, which carry radiating spines at the tip ("paxillae"). Fam. 3. Oreastridae. - Two rows of ambulacral feet; skin granular, pierced by minute pores. Fam. 4. Asterinidae. - Two rows of ambulacral feet; body discoidal or pyramidal, sharp-edged; skeleton of imbricate plates ; dorsal wart single, rarely double. Fam. 5. Brisingidae. - Arms long and rounded, sharply marked off from the disc. Ambulacral grooves not reaching the mouth ; two rows of ambulacral feet.