FYI,
Special issue "Developmental mechanisms, patterning and evolution" in Current Opinion in Genetics and Development.
There's a review article on Platynereis dumerilii, and one on Capitella teleta, plus on other taxa. I think they're open access, at least temporarily.
http://www.sciencedirect.com/science/journal/0959437X/39/supp/C
Seaver, Elaine C. 2016. Annelid models I: Capitella teleta. Current Opinion in Genetics & Development 39: 35-41
Williams, Elizabeth A.; Jékely, Gáspár. 2016. Towards a systems-level understanding of development in the marine annelid Platynereis dumerilii. Current Opinion in Genetics & Development 39: 175-181
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Geoff