It's a real beauty, Jean. Here's a link to a whole gallery of Brassia orchids.ttps://www.google.com/search?q=Brassia+orchids&client=firefox-a&hs=ik9&rls=org.mozilla:en-US:official&tbm=isch&tbo=u&source=univ&sa=X&ei=i8bzUu3mF4mFkQfYlYG4Dw&ved=0CCYQsAQ&biw=1891&bih=910
I didn't see one with the lovely purple markings like yours though. If you had a better picture showing the leaves and base of the plant as well, that might help to ID the specific cross.
Btw, Anne the Brassias are collectively known as "spider orchids" because of the spidery flowers. There are probably hundreds of crosses from plain white to different colors and markings. Here's arcuigera
http://bklynorchids.com/2010/1...
