I've always seen Cameroon Sheep rams with horns - and this German Cameroon Sheep site (yes, there is one!) has a huge picture of a fully-horned ram on it.
I stand corrected. Here in Canada and the US These sheep are called Black-belly and come in two forms, Barbados(Polled) and American(Horned). They may be a distinct breed that just shows a large amount of resemblance.