BadImageFormatException for System.ServiceModel.Web.dll

Hi All,
I'm running into a few exceptions related to System.ServiceModel.Web. According to the documentation, this is an available assembly, but I get errors whenever I try to work with it from my Xamarin.Mac app.

Simply running this code:

            var Data = System.IO.File.ReadAllBytes(@"/Library/Frameworks/Mono.framework/Versions/5.8.0/lib/mono/4.6.1-api/System.ServiceModel.Web.dll");

            System.Reflection.Assembly.Load(Data);

Generates the exception.

Does anyone have any suggestions? Perhaps something is messed up with this assembly?