Your dishes were designed by Margaret Blumenthal in the shape of a sailing vessel called Streamline in 1934
I was a bit confused by your comment above, can you elaborate? For example, the sailing vessel you mention - are you referring to the maker's mark or plate decoration itself?
All I've seen of the 'Monogram' pieces that Jodypenland describes don't have any kind of ship associated with them, and I'd be curious to see yours if they do!
Also, I've collected Salem Tricorne, Streamline & Century shapes extensively, but am unfamiliar with Margaret Blumenthal, can you tell me more about her?