24G Notes on the Embryology of Starfishes. 



of Cribrella is only a modified plateau development, the only 

 traces of which are the club-shaped appendages of the lower 

 side of the young Echinaster. 



The natural attitude of the Torn aria is with the anal extre- 

 mity below, as represented in the accompanying figures. 



Explanation of Lettering. Plate 11. 

 a anus. 



oesophagus. m mouth. 



m' muscle attached to the oral extremity of the conical water-system. 



d stomach, c intestine. 



w oral portion of water-system. 



w' w" isolated anal parts of water-system. 



b water-pore. 



e rudimentary anal arm. 



e' epaulettes of oral chord. 



e" epaulettes of anal chord. 



/ terminal oral arm. 



g horseshoe-shaped groove. 



v anal part of vibratile chord. 



v' oral portion of vibratile chord. 



v" circular anal vibratile chord. 



1 loops of anal vibratile chord. 

 V loops of oral vibratile chord. 



Fig. 1. Young Tornaria seen from the mouth side. 

 Fig. 2. Fig. 1 seen from the side of water-pore. 

 Fig. 3. Somewhat more advanced Tornaria seen in profile. 

 Fig. 4. Fig. 1 seen from the oral extremity. 

 Fig. 5. Fig. 1 seen from the anal extremity. 

 Fig. 6. Older Tornaria seen from the mouth side. 

 Fig. 7. Nearly in the same condition seen from the opposite side. 

 Fig. 8. Fig. 7 seen in profile. 

 Fig. 9. Digestive system isolated, stage of Fig. 1. 

 Fig. 10. Anal portion of the digestive system, stage of Fig. 3. 

 Fig. 11. Young Brachiolaria (Asteracanthion pallidiis, Ac.) intro- 

 duced for comparison. 

 All the figures are greatly magnified. 



