450 



EMBRYOLOGY 



left portions of the body cavity, there is developed still a third part, was 

 already mentioned in considering the hydrocoele (comp. p. 413). 



Fio3. 221 (and 222).— Pentacrinoid larva (C) and svrarming larvse (Ä and B) of 

 Anted'w (after Thomson, from BiLFODR's Comparative Embryolog n). The most 

 anterior ciliated ring, described by Buet, is lacking on the swarming larvse, 

 which are placed in the positions in which thev subsequently become attached 

 (comp. Pig. 217, p. 4i4). 



