knife for id please
 

the handle is ivory, it measures 21 inches long

As with your other daggers, I see a European-style dirk, but I suspect it is either an African or Middle-Eastern interpretation of such. The ribbed ivory/bone hilt and up/down facing quillons appearing Euro, while the overall presentation, including the finial base and blade, appear otherwise. The notches on the blade are common on African weapons. Could it not also be a 'ladder of Allah' decoration as well? Not my area and I'll wait for others to chime in.