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nudibranchiata have nothing to do with gills; and if this be admitted, there 

 is no reason why A. nudibranchiata, like A. antarclica, should not be the 

 larva of a Synaptid, to which group its wheels naturally ally it." Without 

 entering on a discussion of the time of appearance of the gill-rudiments 

 in Cucumaria I would merely point out the fact that there is no structure 

 in the Synaptids into which this pouch could possibly develop. This would 

 then mean that this large organ of the Auricularia should completely dis- 

 appear again on metamorphosis. This is certainly not very likely. The 

 question about the parental origin of this larva can hardly be definitely 

 settled except through the rearing of the larva; it seems only safe to say 

 this much that the intestinal pouch proves that it must belong to some 

 form with gill-trees, and accordingly cannot be a Synaptid, in spite of the 

 Auricularian wheels. 



