y^ EMBKYOLOGY OF THE STARFISH. 



Echinoderms (Starfish, Echini, or Ophiuransj. The changes in the rela- 

 tive position of the organs remind us strongly of the mode in which the 

 Tomaria gradually passes into a Balanoglossus hy a mere difference in 

 the topography of the organs of the Pluteus and of the enclosed Synapta 

 The mode of development of Holothurians seems to be intermediate be- 

 tween the pelasgic pluteus, with its gigantic arms (Starfish, Ophiuran, 

 Echinus) and the sedentary or viviparous development of certain Ophi- 

 urans. Starfishes, and Echini. See also the excellent paper l)y Selenka on 

 Holothuria in Zeitscrif. Wiss. Zool., \^ol. XXYIl.] 



