The Acorn Worm genomes just written up in Nature are not easy to search.
Saccoglossus kowalevskii does have GeneBank entries coveing the genome
but _Ptychodera flava_ does not
It appears to be DDBJ only at the moment
Any chance Emily_Ensembl the authors could be prevailed upon to submit thier assemblies to Ensembl gene builds? That would give the rest of us the chance to do our own comparisons