ECHINODERMA TA 



231 



Pig. 133.— The common Starfish {AsUrias ruhens), dissected to show motor, digestive, 

 and reproductive systems. After Eolleston and Jackson. 



1. Central radius of trivlum. 



2. Right arm of trivium. 



3. Left arm of trivium. 



4. Left arm of bivium. 



5. Eight arm of bivium. 



6. Madreporio plate and canal. 



7. Arborescent "hepatic" caeca, two in 



each arm. 



8. Generative glands. 



9. Ampullae of tube-feet. 



10. Ambulacral plates, inner surface. 



11. Pyloric portion of stomach. 



12. Duct leading from stomach to paired 



caeca. 



13. Cardiac division of stomach bulging 



into arm. 



14. Anus. 



