Fish Emblem?

The brochure for the 68 Barracuda does show the fish in the circle on the trunk lid. Whether they are different I don't know mine doesn't have one either and no holes for it, but on the inner structure there are two holes in the bracing.

Here's a picture.
View attachment scan0001.jpg

Looking at the brochure close it does look as thought it sticks up , but it's not that good of a picture it could just be a shadow.