STAGE "B". 42 BDURS. 



According to BURY(2) .the hydrocoele does not 

 have the sams origin in all the groups of echinoderms: 

 he found that it originates in the crinoids , sea- 

 urchins and star-fishes from the left antorftor ent- 

 erocoele but in the ophiurids it grows out from the 

 anterior end of the left posterior enterccoele . 



This observation which BURY records with appar- 

 ent hesitation, I can completely confirm as will be 

 seen in the description and figures of "B" . 



Externally the appearance is the same as in 

 "A" but the internal structures have undergone a 

 great change. 



The anterior pouches, the cavities of which 

 in aA" were connected both with each other and with 

 the cavity of the archenteron,are now separate and 

 distinct. The connection between these structures 

 still continues however in their fused walls. She 

 left pouch is a little larger than the right and 

 lies behind and to the left of the latter; fu if asJi. 



Just below the anterior' pouches there is to 



be found a third pouch which is growing out from the 



left side and anterior end of the archenteron. It 



UMA. 



protrudes anteriorly and partially the two anterior 



