THE HOLOTHURIDEA. 



471 



Fts. ^BQ.—S}/napta diqifata and hihcerms (After Banr.) ^ 



A, ]arva wirh the bilateral ciliated band, and wheel-shaped calcareons plates: 

 ventral view, a, mouth and j^iHet ; b, stomach; c, intestine and anus; d, sacs 

 of the enterofcele (sausatre-shaped Vodies) at the sides of the stomach ; e, rudi- 

 ment of the ambulacra! vascular system. B, further advanced condition ot the 

 larva in which the oral aperture is obsolete (the so-called " pupa-stace "). and the 

 cilia are arranged in zones, i, tentacula; Jc, Polian vesicle ; /, the longitudinal 

 muscles of the bodv-wall. C. a voun? Synapta, in which the ciliated zones liave 

 disappeared ; with" its five tentacles and the wheel-shaped calcareous bodies at 

 its hinder end. m, the madrenoric canal which now opens into the cavity of the 

 body. D. a voun^^ Synapta whcerens with anchor-shaped calcareous spicula, ex- 

 cept at the hinder end of the body, where they are small and polygonal. E, lon- 



» "Beitryge zur Naturgeschiclite der Synapta digitata,''^ ("Nova Acta,'* 

 xxxi., 1864.) 



