I'm submitting right now and some agents don't give information on whether or not to send in artwork. I have several maps, that aren't really vital to the story but really help the reader to visualise the world. Do I send in copies or do I just leave it and mention the artwork in my covering letter?
The agents submission criteria I've read so far say they don't want you to include maps. Initially, most just want a covering letter, synopsis and the first three chapters--or up to about 50 pages--of your work. I would just mention it in the covering letter and if they're keen on the story, you could sent the maps along with the full story when they request it.
Hope that helps.