Yep. Here's one of many results of Google search on "swamped rib":

http://www.hallowellco.com/swamped_rib%20definition.htm

"Swamped Rib - A minimalist, smooth, concave, practically hidden, top rib on a side-by-side gun that connects the two barrels together, but provides no obvious extra aid to pointing---leaving the whole silhouette of the barrels themselves as the shooter's frame of reference."