"Handbook of Normal Penaeid Shrimp Histology" is a fairly good book for general anatomy and histology. Not specifically Mysid and Euphausiid but the anatomy isn't far different if you are looking at general digestive, reproductive, nervous systems etc

Thanks for the info, I'll try to find the book.

This reference will be useful (It's online): Heard, R.W. et al. (2006) A Taxonomic Guide to the Mysids of South Atlantic Bight.

Andres

Thank you for the interesting taxonomic guide it will certainly help. But I look, and I should made that more clear, for a book about the internal anatomy.