Decussated CNS?

[Harry Erwin]

Examination of tunicate tadpoles would be appropriate to help answer this
question. Has anyone done the necessary work? Back in 1968, Romer
speculated that the chordate CNS was an innovation of the larval stage of
a sessile filter-feeding adult. 

Cheers,
-- 
Harry Erwin
Internet: erwin at trwacs.fp.trw.com