74 EMBRYOLOCxY OF THE STARFISH. 



Echinoderms (Slarfisli, Echini, or Ophiurans). The changes in the rela- 

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

 Toruaria gradually passes into a Balanoglossus by a mere diflference in 

 the topography of the organs of the Piute us 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- 

 in\ans, Starfishes, and Echini. See also the excellent paper by Selenka. on 

 Holothuria in Zeitscrif. Wiss. Zool., Vol. XXVIl.] 



