~ASTROPECTINIDÆ~ ^Astropecten^ ^A. articularis^ ^Psilaster^ ^P. floræ^ ^Luidia^ ^L. senegalensis^ ^L. clathrata^ ^L. alternata^ ~PENTAGONASTERIDÆ~ ^Mediaster^ ^M. æqualis^ ~ANTHENEIDÆ~ ^Hippasteria^ ^H. phrygiana^ ~PENTACEROTIDÆ~ ^Pentaceros^ ^P. occidentalis^ ^P. reticularis^ ^Nidorella^ ^N. armata^ ~ASTERINIDÆ~ ^Asterina^ ^A. folium^ ^A. miniata^ Order =CRYPTOZONIA= (/Ossicles crowded; pedicellariæ stalked/) ~SOLASTERIDÆ~ ^Solaster^ ^S. endeca^ ^S. decemradiata^ ^Crossaster^ ^C. papposus^ ~ECHINASTERIDÆ~ ^Cribrella^ ^C. sanguinolenta^ ^Echinaster^ ^E. sentus^ ~HELIASTERIDÆ~ ^Heliaster^ ^H. multiradiata^ ~ASTERIIDÆ~ ^Asterias^ ^A. vulgaris^ ^A. Forbesii^ ^A. ochracea^ ^A. gigantea^ [pg205] CLASS =ASTEROIDEA= THE STARFISHES These animals are named from their star-shaped outline. Some have five long, spreading arms diverging from a small disk, which is hardly more than their point of union; others have a large body with short arms, which are like angular projections of the body, giving a pentagonal shape. Some genera have a greater number of arms than others; /Solaster/ has eleven to thirteen, and /Heliaster/ (the sun-stars, found on the west tropical coast) has thirty to forty. [Illustration: Diagram of water-vascular system of a starfish: /a/, madreporite; /b/, stone-canal; /c/, ring-canal; /d/, radial canals; /e/, ampullæ; /f/, ambulacra.]